diff --git a/README.md b/README.md
index bf963add..6ac09274 100644
--- a/README.md
+++ b/README.md
@@ -142,7 +142,7 @@ Before submitting design contributions, please discuss them with the Standard Eb
 
 - Include in-use ebook slug as a search parameter when searching for artwork by keyword.
 
-- Artwork searching/filtering should be done in pure SQL, no after-sql filtering in PHP.
+- Artwork searching/filtering should be done in pure SQL, no after-SQL filtering in PHP.
 
 - Allow listing artwork by artist by visiting `/artworks/<artist-name>`, and link instances of artist name to that URL.
 
diff --git a/lib/Artist.php b/lib/Artist.php
index 4c18a478..850423e7 100644
--- a/lib/Artist.php
+++ b/lib/Artist.php
@@ -85,7 +85,7 @@ class Artist extends PropertiesBase{
 
 	public static function Get(?int $artistId): Artist{
 		if($artistId === null){
-			throw new Exceptions\InvalidArtistException();
+			throw new Exceptions\ArtistNotFoundException();
 		}
 
 		$result = Db::Query('
@@ -95,7 +95,7 @@ class Artist extends PropertiesBase{
 			', [$artistId], 'Artist');
 
 		if(sizeof($result) == 0){
-			throw new Exceptions\InvalidArtistException();
+			throw new Exceptions\ArtistNotFoundException();
 		}
 
 		return $result[0];
diff --git a/lib/Artwork.php b/lib/Artwork.php
index 1e931e7a..5074fc48 100644
--- a/lib/Artwork.php
+++ b/lib/Artwork.php
@@ -135,7 +135,7 @@ class Artwork extends PropertiesBase{
 			try{
 				$this->_Submitter = User::Get($this->SubmitterUserId);
 			}
-			catch(Exceptions\InvalidUserException){
+			catch(Exceptions\UserNotFoundException){
 				// Return null
 			}
 		}
@@ -148,7 +148,7 @@ class Artwork extends PropertiesBase{
 			try{
 				$this->_Reviewer = User::Get($this->ReviewerUserId);
 			}
-			catch(Exceptions\InvalidUserException){
+			catch(Exceptions\UserNotFoundException){
 				// Return null
 			}
 		}
@@ -486,7 +486,7 @@ class Artwork extends PropertiesBase{
 		// But we do a basic check that the string includes one _. It might not include a dash, for example anonymous_poetry
 		if($this->EbookWwwFilesystemPath !== null){
 			if(mb_stripos($this->EbookWwwFilesystemPath, '_') === false){
-				$error->Add(new Exceptions\InvalidEbookException('Invalid ebook. Expected file system slug like “c-s-lewis_poetry”.'));
+				$error->Add(new Exceptions\EbookNotFoundException('Invalid ebook. Expected file system slug like “c-s-lewis_poetry”.'));
 			}
 		}
 
@@ -900,23 +900,23 @@ class Artwork extends PropertiesBase{
 		$artwork = new Artwork();
 		$artwork->Artist = new Artist();
 
-		$artwork->Artist->Name = HttpInput::Str(POST, 'artist-name', false);
+		$artwork->Artist->Name = HttpInput::Str(POST, 'artist-name');
 		$artwork->Artist->DeathYear = HttpInput::Int(POST, 'artist-year-of-death');
 
-		$artwork->Name = HttpInput::Str(POST, 'artwork-name', false);
+		$artwork->Name = HttpInput::Str(POST, 'artwork-name');
 		$artwork->CompletedYear = HttpInput::Int(POST, 'artwork-year');
-		$artwork->CompletedYearIsCirca = HttpInput::Bool(POST, 'artwork-year-is-circa', false) ?? false;
-		$artwork->Tags = HttpInput::Str(POST, 'artwork-tags', false) ?? [];
-		$artwork->Status = HttpInput::Str(POST, 'artwork-status', false) ?? ArtworkStatus::Unverified;
-		$artwork->EbookWwwFilesystemPath = HttpInput::Str(POST, 'artwork-ebook-www-filesystem-path', false);
-		$artwork->IsPublishedInUs = HttpInput::Bool(POST, 'artwork-is-published-in-us', false);
+		$artwork->CompletedYearIsCirca = HttpInput::Bool(POST, 'artwork-year-is-circa') ?? false;
+		$artwork->Tags = HttpInput::Str(POST, 'artwork-tags') ?? [];
+		$artwork->Status = HttpInput::Str(POST, 'artwork-status') ?? ArtworkStatus::Unverified;
+		$artwork->EbookWwwFilesystemPath = HttpInput::Str(POST, 'artwork-ebook-www-filesystem-path');
+		$artwork->IsPublishedInUs = HttpInput::Bool(POST, 'artwork-is-published-in-us') ?? false;
 		$artwork->PublicationYear = HttpInput::Int(POST, 'artwork-publication-year');
-		$artwork->PublicationYearPageUrl = HttpInput::Str(POST, 'artwork-publication-year-page-url', false);
-		$artwork->CopyrightPageUrl = HttpInput::Str(POST, 'artwork-copyright-page-url', false);
-		$artwork->ArtworkPageUrl = HttpInput::Str(POST, 'artwork-artwork-page-url', false);
-		$artwork->MuseumUrl = HttpInput::Str(POST, 'artwork-museum-url', false);
-		$artwork->Exception = HttpInput::Str(POST, 'artwork-exception', false);
-		$artwork->Notes = HttpInput::Str(POST, 'artwork-notes', false);
+		$artwork->PublicationYearPageUrl = HttpInput::Str(POST, 'artwork-publication-year-page-url');
+		$artwork->CopyrightPageUrl = HttpInput::Str(POST, 'artwork-copyright-page-url');
+		$artwork->ArtworkPageUrl = HttpInput::Str(POST, 'artwork-artwork-page-url');
+		$artwork->MuseumUrl = HttpInput::Str(POST, 'artwork-museum-url');
+		$artwork->Exception = HttpInput::Str(POST, 'artwork-exception');
+		$artwork->Notes = HttpInput::Str(POST, 'artwork-notes');
 
 		return $artwork;
 	}
diff --git a/lib/Ebook.php b/lib/Ebook.php
index a287069c..3674196f 100644
--- a/lib/Ebook.php
+++ b/lib/Ebook.php
@@ -91,20 +91,20 @@ class Ebook{
 			}
 			catch(Exception){
 				// We may get an exception from preg_replace if the passed repo wwwFilesystemPath contains invalid UTF-8 characters, whichis  a common injection attack vector
-				throw new Exceptions\InvalidEbookException('Invalid repo filesystem path: ' . $this->RepoFilesystemPath);
+				throw new Exceptions\EbookNotFoundException('Invalid repo filesystem path: ' . $this->RepoFilesystemPath);
 			}
 		}
 
 		if(!is_dir($wwwFilesystemPath)){
-			throw new Exceptions\InvalidEbookException('Invalid www filesystem path: ' . $wwwFilesystemPath);
+			throw new Exceptions\EbookNotFoundException('Invalid www filesystem path: ' . $wwwFilesystemPath);
 		}
 
 		if(!is_dir($this->RepoFilesystemPath)){
-			throw new Exceptions\InvalidEbookException('Invalid repo filesystem path: ' . $this->RepoFilesystemPath);
+			throw new Exceptions\EbookNotFoundException('Invalid repo filesystem path: ' . $this->RepoFilesystemPath);
 		}
 
 		if(!is_file($wwwFilesystemPath . '/content.opf')){
-			throw new Exceptions\InvalidEbookException('Invalid content.opf file: ' . $wwwFilesystemPath . '/content.opf');
+			throw new Exceptions\EbookNotFoundException('Invalid content.opf file: ' . $wwwFilesystemPath . '/content.opf');
 		}
 
 		$this->WwwFilesystemPath = $wwwFilesystemPath;
diff --git a/lib/Exceptions/InvalidArtistException.php b/lib/Exceptions/ArtistNotFoundException.php
similarity index 62%
rename from lib/Exceptions/InvalidArtistException.php
rename to lib/Exceptions/ArtistNotFoundException.php
index b4fd38d5..67e0a3d8 100644
--- a/lib/Exceptions/InvalidArtistException.php
+++ b/lib/Exceptions/ArtistNotFoundException.php
@@ -1,6 +1,6 @@
 <?
 namespace Exceptions;
 
-class InvalidArtistException extends AppException{
+class ArtistNotFoundException extends AppException{
 	protected $message = 'We couldn’t locate that artist.';
 }
diff --git a/lib/Exceptions/AuthorNotFoundException.php b/lib/Exceptions/AuthorNotFoundException.php
new file mode 100644
index 00000000..74509f8f
--- /dev/null
+++ b/lib/Exceptions/AuthorNotFoundException.php
@@ -0,0 +1,5 @@
+<?
+namespace Exceptions;
+
+class AuthorNotFoundException extends AppException{
+}
diff --git a/lib/Exceptions/CollectionNotFoundException.php b/lib/Exceptions/CollectionNotFoundException.php
new file mode 100644
index 00000000..9716e0fa
--- /dev/null
+++ b/lib/Exceptions/CollectionNotFoundException.php
@@ -0,0 +1,5 @@
+<?
+namespace Exceptions;
+
+class CollectionNotFoundException extends AppException{
+}
diff --git a/lib/Exceptions/EbookNotFoundException.php b/lib/Exceptions/EbookNotFoundException.php
new file mode 100644
index 00000000..41758149
--- /dev/null
+++ b/lib/Exceptions/EbookNotFoundException.php
@@ -0,0 +1,5 @@
+<?
+namespace Exceptions;
+
+class EbookNotFoundException extends AppException{
+}
diff --git a/lib/Exceptions/InvalidAuthorException.php b/lib/Exceptions/InvalidAuthorException.php
deleted file mode 100644
index 4e4fa05e..00000000
--- a/lib/Exceptions/InvalidAuthorException.php
+++ /dev/null
@@ -1,5 +0,0 @@
-<?
-namespace Exceptions;
-
-class InvalidAuthorException extends AppException{
-}
diff --git a/lib/Exceptions/InvalidCollectionException.php b/lib/Exceptions/InvalidCollectionException.php
deleted file mode 100644
index 83897dc5..00000000
--- a/lib/Exceptions/InvalidCollectionException.php
+++ /dev/null
@@ -1,5 +0,0 @@
-<?
-namespace Exceptions;
-
-class InvalidCollectionException extends AppException{
-}
diff --git a/lib/Exceptions/InvalidEbookException.php b/lib/Exceptions/InvalidEbookException.php
deleted file mode 100644
index 0ba51e9d..00000000
--- a/lib/Exceptions/InvalidEbookException.php
+++ /dev/null
@@ -1,5 +0,0 @@
-<?
-namespace Exceptions;
-
-class InvalidEbookException extends AppException{
-}
diff --git a/lib/Exceptions/InvalidSessionException.php b/lib/Exceptions/InvalidSessionException.php
deleted file mode 100644
index 90930d23..00000000
--- a/lib/Exceptions/InvalidSessionException.php
+++ /dev/null
@@ -1,5 +0,0 @@
-<?
-namespace Exceptions;
-
-class InvalidSessionException extends AppException{
-}
diff --git a/lib/Exceptions/InvalidNewsletterSubscriptionException.php b/lib/Exceptions/NewsletterSubscriptionNotFoundException.php
similarity index 62%
rename from lib/Exceptions/InvalidNewsletterSubscriptionException.php
rename to lib/Exceptions/NewsletterSubscriptionNotFoundException.php
index 0c55f4e0..fde14f8c 100644
--- a/lib/Exceptions/InvalidNewsletterSubscriptionException.php
+++ b/lib/Exceptions/NewsletterSubscriptionNotFoundException.php
@@ -1,6 +1,6 @@
 <?
 namespace Exceptions;
 
-class InvalidNewsletterSubscriptionException extends AppException{
+class NewsletterSubscriptionNotFoundException extends AppException{
 	protected $message = 'We couldn’t find you in our newsletter subscribers list.';
 }
diff --git a/lib/Exceptions/InvalidPollItemException.php b/lib/Exceptions/PollItemNotFoundException.php
similarity index 62%
rename from lib/Exceptions/InvalidPollItemException.php
rename to lib/Exceptions/PollItemNotFoundException.php
index c3fd6753..87e6d722 100644
--- a/lib/Exceptions/InvalidPollItemException.php
+++ b/lib/Exceptions/PollItemNotFoundException.php
@@ -1,6 +1,6 @@
 <?
 namespace Exceptions;
 
-class InvalidPollItemException extends AppException{
+class PollItemNotFoundException extends AppException{
 	protected $message = 'We couldn’t locate that poll item.';
 }
diff --git a/lib/Exceptions/InvalidPollException.php b/lib/Exceptions/PollNotFoundException.php
similarity index 62%
rename from lib/Exceptions/InvalidPollException.php
rename to lib/Exceptions/PollNotFoundException.php
index cda0f6c5..7fc26b44 100644
--- a/lib/Exceptions/InvalidPollException.php
+++ b/lib/Exceptions/PollNotFoundException.php
@@ -1,6 +1,6 @@
 <?
 namespace Exceptions;
 
-class InvalidPollException extends AppException{
+class PollNotFoundException extends AppException{
 	protected $message = 'We couldn’t locate that poll.';
 }
diff --git a/lib/Exceptions/InvalidPollVoteException.php b/lib/Exceptions/PollVoteNotFoundException.php
similarity index 61%
rename from lib/Exceptions/InvalidPollVoteException.php
rename to lib/Exceptions/PollVoteNotFoundException.php
index 04dd4934..a5bf261f 100644
--- a/lib/Exceptions/InvalidPollVoteException.php
+++ b/lib/Exceptions/PollVoteNotFoundException.php
@@ -1,6 +1,6 @@
 <?
 namespace Exceptions;
 
-class InvalidPollVoteException extends AppException{
+class PollVoteNotFoundException extends AppException{
 	protected $message = 'We couldn’t locate that vote.';
 }
diff --git a/lib/Exceptions/SessionNotFoundException.php b/lib/Exceptions/SessionNotFoundException.php
new file mode 100644
index 00000000..d64e4a92
--- /dev/null
+++ b/lib/Exceptions/SessionNotFoundException.php
@@ -0,0 +1,5 @@
+<?
+namespace Exceptions;
+
+class SessionNotFoundException extends AppException{
+}
diff --git a/lib/Exceptions/InvalidUserException.php b/lib/Exceptions/UserNotFoundException.php
similarity index 62%
rename from lib/Exceptions/InvalidUserException.php
rename to lib/Exceptions/UserNotFoundException.php
index b270a3ba..8b6c8731 100644
--- a/lib/Exceptions/InvalidUserException.php
+++ b/lib/Exceptions/UserNotFoundException.php
@@ -1,6 +1,6 @@
 <?
 namespace Exceptions;
 
-class InvalidUserException extends AppException{
+class UserNotFoundException extends AppException{
 	protected $message = 'We couldn’t locate that user.';
 }
diff --git a/lib/HttpInput.php b/lib/HttpInput.php
index a2caed57..47d9336c 100644
--- a/lib/HttpInput.php
+++ b/lib/HttpInput.php
@@ -50,30 +50,30 @@ class HttpInput{
 		return preg_match('/\btext\/html\b/ius', $_SERVER['HTTP_ACCEPT'] ?? '') ? WEB : REST;
 	}
 
-	public static function Str(string $type, string $variable, bool $allowEmptyString = true, string $default = null): ?string{
-		$var = self::GetHttpVar($variable, HTTP_VAR_STR, $type, $default);
+	public static function Str(string $type, string $variable, $allowEmptyString = false): ?string{
+		$var = self::GetHttpVar($variable, HTTP_VAR_STR, $type);
 
 		if(is_array($var)){
-			return $default;
+			return null;
 		}
 
-		if(!$allowEmptyString && $var === ''){
+		if(!$allowEmptyString && $var == ''){
 			return null;
 		}
 
 		return $var;
 	}
 
-	public static function Int(string $type, string $variable, int $default = null): ?int{
-		return self::GetHttpVar($variable, HTTP_VAR_INT, $type, $default);
+	public static function Int(string $type, string $variable): ?int{
+		return self::GetHttpVar($variable, HTTP_VAR_INT, $type);
 	}
 
-	public static function Bool(string $type, string $variable, bool $default = null): ?bool{
-		return self::GetHttpVar($variable, HTTP_VAR_BOOL, $type, $default);
+	public static function Bool(string $type, string $variable): ?bool{
+		return self::GetHttpVar($variable, HTTP_VAR_BOOL, $type);
 	}
 
-	public static function Dec(string $type, string $variable, float $default = null): ?float{
-		return self::GetHttpVar($variable, HTTP_VAR_DEC, $type, $default);
+	public static function Dec(string $type, string $variable): ?float{
+		return self::GetHttpVar($variable, HTTP_VAR_DEC, $type);
 	}
 
 	/**
@@ -81,11 +81,11 @@ class HttpInput{
 	* @param array<mixed> $default
 	* @return array<string>
 	*/
-	public static function GetArray(string $variable, array $default = null): ?array{
-		return self::GetHttpVar($variable, HTTP_VAR_ARRAY, GET, $default);
+	public static function GetArray(string $variable): ?array{
+		return self::GetHttpVar($variable, HTTP_VAR_ARRAY, GET);
 	}
 
-	private static function GetHttpVar(string $variable, int $type, string $set, mixed $default): mixed{
+	private static function GetHttpVar(string $variable, int $type, string $set): mixed{
 		$vars = [];
 
 		switch($set){
@@ -110,7 +110,7 @@ class HttpInput{
 			}
 			elseif($type !== HTTP_VAR_ARRAY && is_array($vars[$variable])){
 				// We asked for not an array, but we got an array
-				return $default;
+				return null;
 			}
 			else{
 				$var = trim($vars[$variable]);
@@ -126,7 +126,7 @@ class HttpInput{
 							return intval($var);
 						}
 						catch(Exception){
-							return $default;
+							return null;
 						}
 					}
 					break;
@@ -143,13 +143,13 @@ class HttpInput{
 							return floatval($var);
 						}
 						catch(Exception){
-							return $default;
+							return null;
 						}
 					}
 					break;
 			}
 		}
 
-		return $default;
+		return null;
 	}
 }
diff --git a/lib/NewsletterSubscription.php b/lib/NewsletterSubscription.php
index 2690a997..3b07e083 100644
--- a/lib/NewsletterSubscription.php
+++ b/lib/NewsletterSubscription.php
@@ -38,7 +38,7 @@ class NewsletterSubscription extends PropertiesBase{
 		try{
 			$this->User = User::GetByEmail($this->User->Email);
 		}
-		catch(Exceptions\InvalidUserException){
+		catch(Exceptions\UserNotFoundException){
 			// User doesn't exist, create the user
 			$this->User->Create();
 		}
@@ -132,7 +132,11 @@ class NewsletterSubscription extends PropertiesBase{
 	// ORM METHODS
 	// ***********
 
-	public static function Get(string $uuid): NewsletterSubscription{
+	public static function Get(?string $uuid): NewsletterSubscription{
+		if($uuid === null){
+			throw new Exceptions\NewsletterSubscriptionNotFoundException();
+		}
+
 		$result = Db::Query('
 				SELECT ns.*
 				from NewsletterSubscriptions ns
@@ -141,7 +145,7 @@ class NewsletterSubscription extends PropertiesBase{
 			', [$uuid], 'NewsletterSubscription');
 
 		if(sizeof($result) == 0){
-			throw new Exceptions\InvalidNewsletterSubscriptionException();
+			throw new Exceptions\NewsletterSubscriptionNotFoundException();
 		}
 
 		return $result[0];
diff --git a/lib/Payment.php b/lib/Payment.php
index 0882c3a4..0c397e4a 100644
--- a/lib/Payment.php
+++ b/lib/Payment.php
@@ -39,7 +39,7 @@ class Payment extends PropertiesBase{
 						where UserId = ?
 					', [$this->User->Name, $this->User->UserId]);
 				}
-				catch(Exceptions\InvalidUserException){
+				catch(Exceptions\UserNotFoundException){
 					// User doesn't exist, create it now
 					$this->User->Create();
 				}
diff --git a/lib/Poll.php b/lib/Poll.php
index e0e1277d..00c87992 100644
--- a/lib/Poll.php
+++ b/lib/Poll.php
@@ -100,7 +100,7 @@ class Poll extends PropertiesBase{
 
 	public static function Get(?int $pollId): Poll{
 		if($pollId === null){
-			throw new Exceptions\InvalidPollException();
+			throw new Exceptions\PollNotFoundException();
 		}
 
 		$result = Db::Query('
@@ -110,7 +110,7 @@ class Poll extends PropertiesBase{
 				', [$pollId], 'Poll');
 
 		if(sizeof($result) == 0){
-			throw new Exceptions\InvalidPollException();
+			throw new Exceptions\PollNotFoundException();
 		}
 
 		return $result[0];
@@ -118,7 +118,7 @@ class Poll extends PropertiesBase{
 
 	public static function GetByUrlName(?string $urlName): Poll{
 		if($urlName === null){
-			throw new Exceptions\InvalidPollException();
+			throw new Exceptions\PollNotFoundException();
 		}
 
 		$result = Db::Query('
@@ -128,7 +128,7 @@ class Poll extends PropertiesBase{
 				', [$urlName], 'Poll');
 
 		if(sizeof($result) == 0){
-			throw new Exceptions\InvalidPollException();
+			throw new Exceptions\PollNotFoundException();
 		}
 
 		return $result[0];
diff --git a/lib/PollItem.php b/lib/PollItem.php
index 6b56387a..9f98dae2 100644
--- a/lib/PollItem.php
+++ b/lib/PollItem.php
@@ -36,7 +36,7 @@ class PollItem extends PropertiesBase{
 
 	public static function Get(?int $pollItemId): PollItem{
 		if($pollItemId === null ){
-			throw new Exceptions\InvalidPollItemException();
+			throw new Exceptions\PollItemNotFoundException();
 		}
 
 		$result = Db::Query('
@@ -46,7 +46,7 @@ class PollItem extends PropertiesBase{
 				', [$pollItemId], 'PollItem');
 
 		if(sizeof($result) == 0){
-			throw new Exceptions\InvalidPollItemException();
+			throw new Exceptions\PollItemNotFoundException();
 		}
 
 		return $result[0];
diff --git a/lib/PollVote.php b/lib/PollVote.php
index b4cb0203..88a4ca03 100644
--- a/lib/PollVote.php
+++ b/lib/PollVote.php
@@ -36,7 +36,7 @@ class PollVote extends PropertiesBase{
 		$error = new Exceptions\ValidationException();
 
 		if($this->User === null){
-			$error->Add(new Exceptions\InvalidUserException());
+			$error->Add(new Exceptions\UserNotFoundException());
 		}
 
 		if($this->PollItemId === null){
@@ -44,11 +44,11 @@ class PollVote extends PropertiesBase{
 		}
 		else{
 			if($this->PollItem === null){
-				$error->Add(new Exceptions\InvalidPollException());
+				$error->Add(new Exceptions\PollNotFoundException());
 			}
 			else{
 				if($this->PollItem->Poll === null){
-					$error->Add(new Exceptions\InvalidPollException());
+					$error->Add(new Exceptions\PollNotFoundException());
 				}
 				else{
 					if(!$this->PollItem->Poll->IsActive()){
@@ -67,7 +67,7 @@ class PollVote extends PropertiesBase{
 				$vote = PollVote::Get($this->PollItem->Poll->UrlName, $this->UserId);
 				$error->Add(new Exceptions\PollVoteExistsException($vote));
 			}
-			catch(Exceptions\InvalidPollVoteException){
+			catch(Exceptions\PollVoteNotFoundException){
 				// User hasn't voted yet, carry on
 			}
 
@@ -87,7 +87,7 @@ class PollVote extends PropertiesBase{
 				$this->User = User::GetByEmail($email);
 				$this->UserId = $this->User->UserId;
 			}
-			catch(Exceptions\InvalidUserException){
+			catch(Exceptions\UserNotFoundException){
 				// Can't validate patron email - do nothing for now,
 				// this will be caught later when we validate the vote during creation.
 				// Save the email in the User object in case we want it later,
@@ -109,7 +109,7 @@ class PollVote extends PropertiesBase{
 
 	public static function Get(?string $pollUrlName, ?int $userId): PollVote{
 		if($pollUrlName === null || $userId === null){
-			throw new Exceptions\InvalidPollVoteException();
+			throw new Exceptions\PollVoteNotFoundException();
 		}
 
 		$result = Db::Query('
@@ -124,7 +124,7 @@ class PollVote extends PropertiesBase{
 				', [$pollUrlName, $userId], 'PollVote');
 
 		if(sizeof($result) == 0){
-			throw new Exceptions\InvalidPollVoteException();
+			throw new Exceptions\PollVoteNotFoundException();
 		}
 
 		return $result[0];
diff --git a/lib/Session.php b/lib/Session.php
index e147ea84..8bbd86ec 100644
--- a/lib/Session.php
+++ b/lib/Session.php
@@ -64,7 +64,7 @@ class Session extends PropertiesBase{
 
 			self::SetSessionCookie($this->SessionId);
 		}
-		catch(Exceptions\InvalidUserException){
+		catch(Exceptions\UserNotFoundException){
 			throw new InvalidLoginException();
 		}
 	}
@@ -95,7 +95,7 @@ class Session extends PropertiesBase{
 
 	public static function Get(?string $sessionId): Session{
 		if($sessionId === null){
-			throw new Exceptions\InvalidSessionException();
+			throw new Exceptions\SessionNotFoundException();
 		}
 
 		$result = Db::Query('
@@ -105,7 +105,7 @@ class Session extends PropertiesBase{
 				', [$sessionId], 'Session');
 
 		if(sizeof($result) == 0){
-			throw new Exceptions\InvalidSessionException();
+			throw new Exceptions\SessionNotFoundException();
 		}
 
 		return $result[0];
diff --git a/lib/User.php b/lib/User.php
index 93046b26..d9828531 100644
--- a/lib/User.php
+++ b/lib/User.php
@@ -115,7 +115,7 @@ class User extends PropertiesBase{
 
 	public static function Get(?int $userId): User{
 		if($userId === null){
-			throw new Exceptions\InvalidUserException();
+			throw new Exceptions\UserNotFoundException();
 		}
 
 		$result = Db::Query('
@@ -125,7 +125,7 @@ class User extends PropertiesBase{
 				', [$userId], 'User');
 
 		if(sizeof($result) == 0){
-			throw new Exceptions\InvalidUserException();
+			throw new Exceptions\UserNotFoundException();
 		}
 
 		return $result[0];
@@ -133,7 +133,7 @@ class User extends PropertiesBase{
 
 	public static function GetByEmail(?string $email): User{
 		if($email === null){
-			throw new Exceptions\InvalidUserException();
+			throw new Exceptions\UserNotFoundException();
 		}
 
 		$result = Db::Query('
@@ -143,7 +143,7 @@ class User extends PropertiesBase{
 				', [$email], 'User');
 
 		if(sizeof($result) == 0){
-			throw new Exceptions\InvalidUserException();
+			throw new Exceptions\UserNotFoundException();
 		}
 
 		return $result[0];
@@ -154,7 +154,7 @@ class User extends PropertiesBase{
 		// Emails without that row may only be signed up for the newsletter and thus are not "registered" users
 		// The identifier is either an email or a UUID (api key)
 		if($identifier === null){
-			throw new Exceptions\InvalidUserException();
+			throw new Exceptions\UserNotFoundException();
 		}
 
 		$result = Db::Query('
@@ -166,7 +166,7 @@ class User extends PropertiesBase{
 				', [$identifier, $identifier], 'User');
 
 		if(sizeof($result) == 0){
-			throw new Exceptions\InvalidUserException();
+			throw new Exceptions\UserNotFoundException();
 		}
 
 		if($result[0]->PasswordHash !== null && $password === null){
@@ -175,7 +175,7 @@ class User extends PropertiesBase{
 		}
 
 		if($result[0]->PasswordHash !== null && !password_verify($password ?? '', $result[0]->PasswordHash)){
-			throw new Exceptions\InvalidUserException();
+			throw new Exceptions\UserNotFoundException();
 		}
 
 		return $result[0];
diff --git a/www/artworks/edit.php b/www/artworks/edit.php
index 7f1f6d76..d99efa7f 100644
--- a/www/artworks/edit.php
+++ b/www/artworks/edit.php
@@ -13,7 +13,7 @@ try{
 	}
 
 	if($artwork === null){
-		$artwork = Artwork::GetByUrl(HttpInput::Str(GET, 'artist-url-name', false) ?? '', HttpInput::Str(GET, 'artwork-url-name', false) ?? '');
+		$artwork = Artwork::GetByUrl(HttpInput::Str(GET, 'artist-url-name'), HttpInput::Str(GET, 'artwork-url-name'));
 	}
 
 	if(!$artwork->CanBeEditedBy($GLOBALS['User'])){
diff --git a/www/artworks/get.php b/www/artworks/get.php
index a780310c..bed50f80 100644
--- a/www/artworks/get.php
+++ b/www/artworks/get.php
@@ -3,11 +3,11 @@ use function Safe\session_unset;
 
 session_start();
 
-$saved = HttpInput::Bool(SESSION, 'artwork-saved', false);
+$saved = HttpInput::Bool(SESSION, 'artwork-saved') ?? false;
 $exception = $_SESSION['exception'] ?? null;
 
 try{
-	$artwork = Artwork::GetByUrl(HttpInput::Str(GET, 'artist-url-name') ?? '', HttpInput::Str(GET, 'artwork-url-name') ?? '');
+	$artwork = Artwork::GetByUrl(HttpInput::Str(GET, 'artist-url-name'), HttpInput::Str(GET, 'artwork-url-name'));
 	$isAdminView = $GLOBALS['User']->Benefits->CanReviewArtwork ?? false;
 
 	// If the artwork is not approved, and we're not an admin or the submitter when they can edit, don't show it.
diff --git a/www/artworks/index.php b/www/artworks/index.php
index 2e26c5d3..6dde0d13 100644
--- a/www/artworks/index.php
+++ b/www/artworks/index.php
@@ -1,10 +1,10 @@
 <?
 $page = HttpInput::Int(GET, 'page') ?? 1;
 $perPage = HttpInput::Int(GET, 'per-page') ?? ARTWORK_PER_PAGE;
-$query = HttpInput::Str(GET, 'query', false) ?? '';
-$status = HttpInput::Str(GET, 'status', false) ?? null;
+$query = HttpInput::Str(GET, 'query') ?? '';
+$status = HttpInput::Str(GET, 'status') ?? null;
 $filterArtworkStatus = $status;
-$sort = HttpInput::Str(GET, 'sort', false);
+$sort = HttpInput::Str(GET, 'sort');
 $pages = 0;
 $totalArtworkCount = 0;
 $pageDescription = '';
diff --git a/www/artworks/new.php b/www/artworks/new.php
index 6b2e2f24..dfa165fe 100644
--- a/www/artworks/new.php
+++ b/www/artworks/new.php
@@ -3,7 +3,7 @@ use function Safe\session_unset;
 
 session_start();
 
-$created = HttpInput::Bool(SESSION, 'artwork-created', false);
+$created = HttpInput::Bool(SESSION, 'artwork-created') ?? false;
 $exception = $_SESSION['exception'] ?? null;
 /** @var Artwork $artwork */
 $artwork = $_SESSION['artwork'] ?? null;
diff --git a/www/artworks/post.php b/www/artworks/post.php
index a3644981..7bc91a32 100644
--- a/www/artworks/post.php
+++ b/www/artworks/post.php
@@ -52,7 +52,7 @@ try{
 
 	// PUTing an artwork
 	if($httpMethod == HTTP_PUT){
-		$originalArtwork = Artwork::GetByUrl(HttpInput::Str(GET, 'artist-url-name', false), HttpInput::Str(GET, 'artwork-url-name', false));
+		$originalArtwork = Artwork::GetByUrl(HttpInput::Str(GET, 'artist-url-name'), HttpInput::Str(GET, 'artwork-url-name'));
 
 		if(!$originalArtwork->CanBeEditedBy($GLOBALS['User'])){
 			throw new Exceptions\InvalidPermissionsException();
@@ -65,7 +65,7 @@ try{
 		$artwork->Created = $originalArtwork->Created;
 		$artwork->SubmitterUserId = $originalArtwork->SubmitterUserId;
 
-		$newStatus = ArtworkStatus::tryFrom(HttpInput::Str(POST, 'artwork-status', false) ?? '');
+		$newStatus = ArtworkStatus::tryFrom(HttpInput::Str(POST, 'artwork-status') ?? '');
 		if($newStatus !== null){
 			if($originalArtwork->Status != $newStatus && !$originalArtwork->CanStatusBeChangedBy($GLOBALS['User'])){
 				throw new Exceptions\InvalidPermissionsException();
@@ -97,13 +97,13 @@ try{
 
 	// PATCHing a new artwork
 	if($httpMethod == HTTP_PATCH){
-		$artwork = Artwork::GetByUrl(HttpInput::Str(GET, 'artist-url-name', false), HttpInput::Str(GET, 'artwork-url-name', false));
+		$artwork = Artwork::GetByUrl(HttpInput::Str(GET, 'artist-url-name'), HttpInput::Str(GET, 'artwork-url-name'));
 
 		$exceptionRedirectUrl = $artwork->Url;
 
 		// We can PATCH the status, the ebook www filesystem path, or both.
 
-		$newStatus = ArtworkStatus::tryFrom(HttpInput::Str(POST, 'artwork-status', false) ?? '');
+		$newStatus = ArtworkStatus::tryFrom(HttpInput::Str(POST, 'artwork-status') ?? '');
 		if($newStatus !== null){
 			if($artwork->Status != $newStatus && !$artwork->CanStatusBeChangedBy($GLOBALS['User'])){
 				throw new Exceptions\InvalidPermissionsException();
@@ -112,7 +112,7 @@ try{
 			$artwork->ReviewerUserId = $GLOBALS['User']->UserId;
 		}
 
-		$newEbookWwwFilesystemPath = HttpInput::Str(POST, 'artwork-ebook-www-filesystem-path', false) ?? null;
+		$newEbookWwwFilesystemPath = HttpInput::Str(POST, 'artwork-ebook-www-filesystem-path') ?? null;
 		if($artwork->EbookWwwFilesystemPath != $newEbookWwwFilesystemPath && !$artwork->CanEbookWwwFilesysemPathBeChangedBy($GLOBALS['User'])){
 			throw new Exceptions\InvalidPermissionsException();
 		}
diff --git a/www/bulk-downloads/collection.php b/www/bulk-downloads/collection.php
index 90a38a4b..772c97bc 100644
--- a/www/bulk-downloads/collection.php
+++ b/www/bulk-downloads/collection.php
@@ -3,7 +3,7 @@ use function Safe\apcu_fetch;
 use function Safe\preg_replace;
 
 $canDownload = false;
-$class = HttpInput::Str(GET, 'class', false) ?? '';
+$class = HttpInput::Str(GET, 'class');
 
 if($class != 'authors' && $class != 'collections' && $class != 'subjects' && $class != 'months'){
 	Template::Emit404();
diff --git a/www/bulk-downloads/download.php b/www/bulk-downloads/download.php
index 5d90d3b8..a75d545e 100644
--- a/www/bulk-downloads/download.php
+++ b/www/bulk-downloads/download.php
@@ -1,7 +1,7 @@
 <?
 use function Safe\preg_match;
 
-$path = HttpInput::Str(GET, 'path', false) ?? '';
+$path = HttpInput::Str(GET, 'path') ?? '';
 
 try{
 	$path = '/bulk-downloads/' . $path;
diff --git a/www/bulk-downloads/get.php b/www/bulk-downloads/get.php
index 64ab1746..fd08b626 100644
--- a/www/bulk-downloads/get.php
+++ b/www/bulk-downloads/get.php
@@ -2,9 +2,9 @@
 use function Safe\apcu_fetch;
 
 $collection = null;
-$collectionUrlName = HttpInput::Str(GET, 'collection', false);
+$collectionUrlName = HttpInput::Str(GET, 'collection');
 $collection = null;
-$authorUrlName = HttpInput::Str(GET, 'author', false);
+$authorUrlName = HttpInput::Str(GET, 'author');
 $canDownload = false;
 
 try{
@@ -32,7 +32,7 @@ try{
 		}
 
 		if($collection === null){
-			throw new Exceptions\InvalidCollectionException();
+			throw new Exceptions\CollectionNotFoundException();
 		}
 	}
 
@@ -56,14 +56,14 @@ try{
 		}
 
 		if($collection === null){
-			throw new Exceptions\InvalidAuthorException();
+			throw new Exceptions\AuthorNotFoundException();
 		}
 	}
 }
-catch(Exceptions\InvalidAuthorException){
+catch(Exceptions\AuthorNotFoundException){
 	Template::Emit404();
 }
-catch(Exceptions\InvalidCollectionException){
+catch(Exceptions\CollectionNotFoundException){
 	Template::Emit404();
 }
 
diff --git a/www/ebooks/author.php b/www/ebooks/author.php
index 905dc718..879e9793 100644
--- a/www/ebooks/author.php
+++ b/www/ebooks/author.php
@@ -4,24 +4,24 @@ $author = '';
 $authorUrl = '';
 
 try{
-	$urlPath = trim(str_replace('.', '', HttpInput::Str(GET, 'url-path', true) ?? ''), '/'); // Contains the portion of the URL (without query string) that comes after https://standardebooks.org/ebooks/
+	$urlPath = trim(str_replace('.', '', HttpInput::Str(GET, 'url-path') ?? ''), '/'); // Contains the portion of the URL (without query string) that comes after https://standardebooks.org/ebooks/
 	$wwwFilesystemPath = EBOOKS_DIST_PATH . $urlPath; // Path to the deployed WWW files for this ebook
 
 	if($urlPath == '' || mb_stripos($wwwFilesystemPath, EBOOKS_DIST_PATH) !== 0 || !is_dir($wwwFilesystemPath)){
 		// Ensure the path exists and that the root is in our www directory
-		throw new Exceptions\InvalidAuthorException();
+		throw new Exceptions\AuthorNotFoundException();
 	}
 
 	$ebooks = Library::GetEbooksByAuthor($wwwFilesystemPath);
 
 	if(sizeof($ebooks) == 0){
-		throw new Exceptions\InvalidAuthorException();
+		throw new Exceptions\AuthorNotFoundException();
 	}
 
 	$author =  strip_tags($ebooks[0]->AuthorsHtml);
 	$authorUrl = Formatter::EscapeHtml($ebooks[0]->AuthorsUrl);
 }
-catch(Exceptions\InvalidAuthorException){
+catch(Exceptions\AuthorNotFoundException){
 	Template::Emit404();
 }
 ?><?= Template::Header(['title' => 'Ebooks by ' . $author, 'feedUrl' => str_replace('/ebooks/', '/authors/', $authorUrl), 'feedTitle' => 'Standard Ebooks - Ebooks by ' . $author, 'highlight' => 'ebooks', 'description' => 'All of the Standard Ebooks ebooks by ' . $author]) ?>
diff --git a/www/ebooks/ebook.php b/www/ebooks/ebook.php
index f7c5a9e9..957d41b3 100644
--- a/www/ebooks/ebook.php
+++ b/www/ebooks/ebook.php
@@ -14,12 +14,12 @@ $carousel = [];
 $carouselTag = null;
 
 try{
-	$urlPath = trim(str_replace('.', '', HttpInput::Str(GET, 'url-path', true) ?? ''), '/'); // Contains the portion of the URL (without query string) that comes after https://standardebooks.org/ebooks/
+	$urlPath = trim(str_replace('.', '', HttpInput::Str(GET, 'url-path') ?? ''), '/'); // Contains the portion of the URL (without query string) that comes after https://standardebooks.org/ebooks/
 	$wwwFilesystemPath = EBOOKS_DIST_PATH . $urlPath; // Path to the deployed WWW files for this ebook
 
 	if($urlPath == '' || mb_stripos($wwwFilesystemPath, EBOOKS_DIST_PATH) !== 0){
 		// Ensure the path exists and that the root is in our www directory
-		throw new Exceptions\InvalidEbookException();
+		throw new Exceptions\EbookNotFoundException();
 	}
 	// Were we passed the author and a work but not the translator?
 	// For example:
@@ -104,7 +104,7 @@ catch(Exceptions\SeeOtherEbookException $ex){
 	header('Location: ' . $ex->Url);
 	exit();
 }
-catch(Exceptions\InvalidEbookException){
+catch(Exceptions\EbookNotFoundException){
 	Template::Emit404();
 }
 ?><?= Template::Header(['title' => strip_tags($ebook->TitleWithCreditsHtml) . ' - Free ebook download', 'ogType' => 'book', 'coverUrl' => $ebook->DistCoverUrl, 'highlight' => 'ebooks', 'description' => 'Free epub ebook download of the Standard Ebooks edition of ' . $ebook->Title . ': ' . $ebook->Description]) ?>
diff --git a/www/ebooks/index.php b/www/ebooks/index.php
index 31ed03f1..decaff5a 100644
--- a/www/ebooks/index.php
+++ b/www/ebooks/index.php
@@ -4,11 +4,11 @@ use function Safe\preg_replace;
 try{
 	$page = HttpInput::Int(GET, 'page') ?? 1;
 	$perPage = HttpInput::Int(GET, 'per-page') ?? EBOOKS_PER_PAGE;
-	$query = HttpInput::Str(GET, 'query', false) ?? '';
+	$query = HttpInput::Str(GET, 'query') ?? '';
 	$tags = HttpInput::GetArray('tags') ?? [];
-	$collection = HttpInput::Str(GET, 'collection', false);
-	$view = HttpInput::Str(GET, 'view', false);
-	$sort = HttpInput::Str(GET, 'sort', false);
+	$collection = HttpInput::Str(GET, 'collection');
+	$view = HttpInput::Str(GET, 'view');
+	$sort = HttpInput::Str(GET, 'sort');
 	$pages = 0;
 	$totalEbooks = 0;
 	$collectionObject = null;
@@ -71,7 +71,7 @@ try{
 			$pageHeader = 'Free Ebooks in the ' . Formatter::EscapeHtml($collectionName) . ' ' . ucfirst($collectionType);
 		}
 		else{
-			throw new Exceptions\InvalidCollectionException();
+			throw new Exceptions\CollectionNotFoundException();
 		}
 	}
 	else{
@@ -118,7 +118,7 @@ try{
 		$feedTitle = 'Standard Ebooks - Ebooks in the ' . Formatter::EscapeHtml($collectionName) . ' ' . $collectionType;
 	}
 }
-catch(Exceptions\InvalidCollectionException){
+catch(Exceptions\CollectionNotFoundException){
 	Template::Emit404();
 }
 ?><?= Template::Header(['title' => $pageTitle, 'feedUrl' => $feedUrl, 'feedTitle' => $feedTitle, 'highlight' => 'ebooks', 'description' => $pageDescription]) ?>
diff --git a/www/feeds/atom/search.php b/www/feeds/atom/search.php
index 8fbe3a10..80dcdea4 100644
--- a/www/feeds/atom/search.php
+++ b/www/feeds/atom/search.php
@@ -4,7 +4,7 @@ use Safe\DateTime;
 $ebooks = [];
 
 try{
-	$query = HttpInput::Str(GET, 'query', false) ?? '';
+	$query = HttpInput::Str(GET, 'query') ?? '';
 
 	if($query !== ''){
 		$ebooks = Library::Search($query);
diff --git a/www/feeds/collection.php b/www/feeds/collection.php
index 6de1e069..80f1ceee 100644
--- a/www/feeds/collection.php
+++ b/www/feeds/collection.php
@@ -4,8 +4,8 @@ use function Safe\glob;
 use function Safe\preg_replace;
 use function Safe\usort;
 
-$class = HttpInput::Str(GET, 'class', false) ?? '';
-$type = HttpInput::Str(GET, 'type', false) ?? '';
+$class = HttpInput::Str(GET, 'class') ?? '';
+$type = HttpInput::Str(GET, 'type') ?? '';
 
 if($class != 'authors' && $class != 'collections' && $class != 'subjects'){
 	Template::Emit404();
diff --git a/www/feeds/download.php b/www/feeds/download.php
index 505a5cb7..d0663bbb 100644
--- a/www/feeds/download.php
+++ b/www/feeds/download.php
@@ -5,7 +5,7 @@ use function Safe\preg_match;
 // Basic authorization is handled in Core.php. By the time we get here,
 // a valid user has a session.
 
-$path = HttpInput::Str(GET, 'path', false) ?? '';
+$path = HttpInput::Str(GET, 'path') ?? '';
 
 try{
 	$path = '/feeds/' . $path;
diff --git a/www/feeds/get.php b/www/feeds/get.php
index 71772183..f795e969 100644
--- a/www/feeds/get.php
+++ b/www/feeds/get.php
@@ -1,8 +1,8 @@
 <?
 use function Safe\exec;
 
-$author = HttpInput::Str(GET, 'author', false);
-$collection = HttpInput::Str(GET, 'collection', false);
+$author = HttpInput::Str(GET, 'author');
+$collection = HttpInput::Str(GET, 'collection');
 $name = null;
 $target = null;
 $feedTypes = ['opds', 'atom', 'rss'];
@@ -24,12 +24,12 @@ if($collection !== null){
 
 try{
 	if($target === null || $name === null){
-		throw new Exceptions\InvalidCollectionException();
+		throw new Exceptions\CollectionNotFoundException();
 	}
 
 	$file = WEB_ROOT . '/feeds/opds/' . $name . '/' . $target . '.xml';
 	if(!is_file($file)){
-		throw new Exceptions\InvalidCollectionException();
+		throw new Exceptions\CollectionNotFoundException();
 	}
 
 	$label = exec('attr -g se-label ' . escapeshellarg($file)) ?: basename($file, '.xml');
@@ -48,7 +48,7 @@ try{
 
 	$feedUrl = '/' . $name . '/' . $target;
 }
-catch(Exceptions\InvalidCollectionException){
+catch(Exceptions\CollectionNotFoundException){
 	Template::Emit404();
 }
 ?><?= Template::Header(['title' => $title, 'feedTitle' => $feedTitle, 'feedUrl' => $feedUrl, 'description' => $description]) ?>
diff --git a/www/feeds/opds/search.php b/www/feeds/opds/search.php
index 6717dc4f..7198f394 100644
--- a/www/feeds/opds/search.php
+++ b/www/feeds/opds/search.php
@@ -4,7 +4,7 @@ use Safe\DateTime;
 $ebooks = [];
 
 try{
-	$query = HttpInput::Str(GET, 'query', false) ?? '';
+	$query = HttpInput::Str(GET, 'query') ?? '';
 
 	if($query !== ''){
 		$ebooks = Library::Search($query);
diff --git a/www/feeds/rss/search.php b/www/feeds/rss/search.php
index b653eb30..7e06ebe5 100644
--- a/www/feeds/rss/search.php
+++ b/www/feeds/rss/search.php
@@ -4,7 +4,7 @@ use Safe\DateTime;
 $ebooks = [];
 
 try{
-	$query = HttpInput::Str(GET, 'query', false) ?? '';
+	$query = HttpInput::Str(GET, 'query') ?? '';
 
 	if($query !== ''){
 		$ebooks = Library::Search($query);
diff --git a/www/manual/index.php b/www/manual/index.php
index 9b645187..e2a8352f 100644
--- a/www/manual/index.php
+++ b/www/manual/index.php
@@ -7,7 +7,7 @@ use function Safe\sort;
 
 $currentManual = Manual::GetLatestVersion();
 
-$url = HttpInput::Str(GET, 'url', true) ?? '';
+$url = HttpInput::Str(GET, 'url') ?? '';
 $url = preg_replace('|^/|ius', '', $url);
 $url = preg_replace('|\.php$|ius', '', $url);
 $url = preg_replace('|/$|ius', '', $url);
diff --git a/www/newsletter/subscriptions/confirm.php b/www/newsletter/subscriptions/confirm.php
index 171baf92..181b4219 100644
--- a/www/newsletter/subscriptions/confirm.php
+++ b/www/newsletter/subscriptions/confirm.php
@@ -4,7 +4,7 @@ session_start();
 $subscription = new NewsletterSubscription();
 
 try{
-	$subscription = NewsletterSubscription::Get(HttpInput::Str(GET, 'uuid') ?? '');
+	$subscription = NewsletterSubscription::Get(HttpInput::Str(GET, 'uuid'));
 
 	if(!$subscription->IsConfirmed){
 		$subscription->Confirm();
@@ -14,6 +14,6 @@ try{
 	http_response_code(303);
 	header('Location: ' . $subscription->Url);
 }
-catch(Exceptions\InvalidNewsletterSubscriptionException){
+catch(Exceptions\NewsletterSubscriptionNotFoundException){
 	Template::Emit404();
 }
diff --git a/www/newsletter/subscriptions/delete.php b/www/newsletter/subscriptions/delete.php
index feda432b..a8cd7485 100644
--- a/www/newsletter/subscriptions/delete.php
+++ b/www/newsletter/subscriptions/delete.php
@@ -9,7 +9,7 @@ try{
 		throw new Exceptions\InvalidRequestException();
 	}
 
-	$subscription = NewsletterSubscription::Get(HttpInput::Str(GET, 'uuid') ?? '');
+	$subscription = NewsletterSubscription::Get(HttpInput::Str(GET, 'uuid'));
 	$subscription->Delete();
 
 	if($requestType == REST){
@@ -20,7 +20,7 @@ catch(Exceptions\InvalidRequestException){
 	http_response_code(405);
 	exit();
 }
-catch(Exceptions\InvalidNewsletterSubscriptionException){
+catch(Exceptions\NewsletterSubscriptionNotFoundException){
 	if($requestType == WEB){
 		Template::Emit404();
 	}
diff --git a/www/newsletter/subscriptions/get.php b/www/newsletter/subscriptions/get.php
index 9c336ebc..7290f523 100644
--- a/www/newsletter/subscriptions/get.php
+++ b/www/newsletter/subscriptions/get.php
@@ -13,7 +13,7 @@ try{
 		$created = true;
 	}
 	else{
-		$subscription = NewsletterSubscription::Get(HttpInput::Str(GET, 'uuid', false) ?? '');
+		$subscription = NewsletterSubscription::Get(HttpInput::Str(GET, 'uuid'));
 
 		if(isset($_SESSION['subscription-created']) && $_SESSION['subscription-created'] == $subscription->UserId){
 			$created = true;
diff --git a/www/newsletter/subscriptions/post.php b/www/newsletter/subscriptions/post.php
index a3f841c4..dc5a1e0c 100644
--- a/www/newsletter/subscriptions/post.php
+++ b/www/newsletter/subscriptions/post.php
@@ -13,7 +13,7 @@ $requestType = HttpInput::RequestType();
 
 $subscription = new NewsletterSubscription();
 
-if(HttpInput::Str(POST, 'automationtest', false)){
+if(HttpInput::Str(POST, 'automationtest')){
 	// A bot filled out this form field, which should always be empty. Pretend like we succeeded.
 	if($requestType == WEB){
 		http_response_code(303);
@@ -34,11 +34,11 @@ if(HttpInput::Str(POST, 'automationtest', false)){
 
 try{
 	$subscription->User = new User();
-	$subscription->User->Email = HttpInput::Str(POST, 'email', false);
+	$subscription->User->Email = HttpInput::Str(POST, 'email');
 	$subscription->IsSubscribedToNewsletter = HttpInput::Bool(POST, 'issubscribedtonewsletter') ?? false;
 	$subscription->IsSubscribedToSummary = HttpInput::Bool(POST, 'issubscribedtosummary') ?? false;
 
-	$captcha = HttpInput::Str(SESSION, 'captcha', false) ?? '';
+	$captcha = HttpInput::Str(SESSION, 'captcha') ?? '';
 
 	$exception = new Exceptions\ValidationException();
 
@@ -49,7 +49,7 @@ try{
 		$exception->Add($ex);
 	}
 
-	if($captcha === '' || mb_strtolower($captcha) !== mb_strtolower(HttpInput::Str(POST, 'captcha', false) ?? '')){
+	if($captcha === '' || mb_strtolower($captcha) !== mb_strtolower(HttpInput::Str(POST, 'captcha') ?? '')){
 		$exception->Add(new Exceptions\InvalidCaptchaException());
 	}
 
diff --git a/www/polls/get.php b/www/polls/get.php
index a8ee5734..c4a2c40e 100644
--- a/www/polls/get.php
+++ b/www/polls/get.php
@@ -5,7 +5,7 @@ $poll = new Poll();
 $canVote = true; // Allow non-logged-in users to see the 'vote' button
 
 try{
-	$poll = Poll::GetByUrlName(HttpInput::Str(GET, 'pollurlname', false));
+	$poll = Poll::GetByUrlName(HttpInput::Str(GET, 'pollurlname'));
 
 	if(!$poll->IsActive() && $poll->End !== null && $poll->End < new DateTime()){
 		// If the poll ended, redirect to the results
diff --git a/www/polls/votes/index.php b/www/polls/votes/index.php
index d17eeeba..3e3ebee8 100644
--- a/www/polls/votes/index.php
+++ b/www/polls/votes/index.php
@@ -2,7 +2,7 @@
 $poll = new Poll();
 
 try{
-	$poll = Poll::GetByUrlName(HttpInput::Str(GET, 'pollurlname', false));
+	$poll = Poll::GetByUrlName(HttpInput::Str(GET, 'pollurlname'));
 }
 catch(Exceptions\AppException){
 	Template::Emit404();
diff --git a/www/polls/votes/new.php b/www/polls/votes/new.php
index 133dd0ff..7d0300b6 100644
--- a/www/polls/votes/new.php
+++ b/www/polls/votes/new.php
@@ -19,7 +19,7 @@ try{
 		$vote->User = $GLOBALS['User'];
 	}
 
-	$poll = Poll::GetByUrlName(HttpInput::Str(GET, 'pollurlname', false));
+	$poll = Poll::GetByUrlName(HttpInput::Str(GET, 'pollurlname'));
 
 	try{
 		$vote = PollVote::Get($poll->UrlName, $GLOBALS['User']->UserId);
@@ -27,7 +27,7 @@ try{
 		// Vote was found, don't allow another vote
 		throw new Exceptions\PollVoteExistsException($vote);
 	}
-	catch(Exceptions\InvalidPollVoteException){
+	catch(Exceptions\PollVoteNotFoundException){
 		// Vote was not found, user is OK to vote
 	}
 
@@ -39,7 +39,7 @@ try{
 catch(Exceptions\LoginRequiredException){
 	Template::RedirectToLogin();
 }
-catch(Exceptions\InvalidPollException){
+catch(Exceptions\PollNotFoundException){
 	Template::Emit404();
 }
 catch(Exceptions\PollVoteExistsException $ex){
diff --git a/www/polls/votes/post.php b/www/polls/votes/post.php
index 9e6f3484..ad8378d5 100644
--- a/www/polls/votes/post.php
+++ b/www/polls/votes/post.php
@@ -15,7 +15,7 @@ $vote = new PollVote();
 try{
 	$vote->PollItemId = HttpInput::Int(POST, 'pollitemid');
 
-	$vote->Create(HttpInput::Str(POST, 'email', false));
+	$vote->Create(HttpInput::Str(POST, 'email'));
 
 	session_unset();
 
@@ -38,7 +38,7 @@ catch(Exceptions\AppException $ex){
 
 		// Access via form; 303 redirect to the form, which will emit a 422 Unprocessable Entity
 		http_response_code(303);
-		header('Location: /polls/' . HttpInput::Str(GET, 'pollurlname', false) . '/votes/new');
+		header('Location: /polls/' . (HttpInput::Str(GET, 'pollurlname') ?? '') . '/votes/new');
 	}
 	else{
 		// Access via REST api; 422 Unprocessable Entity
diff --git a/www/sessions/new.php b/www/sessions/new.php
index 0fa6e798..be7fe533 100644
--- a/www/sessions/new.php
+++ b/www/sessions/new.php
@@ -8,8 +8,8 @@ if($GLOBALS['User'] !== null){
 	exit();
 }
 
-$email = HttpInput::Str(SESSION, 'email', false);
-$redirect = HttpInput::Str(SESSION, 'redirect', false) ?? HttpInput::Str(GET, 'redirect', false);
+$email = HttpInput::Str(SESSION, 'email');
+$redirect = HttpInput::Str(SESSION, 'redirect') ?? HttpInput::Str(GET, 'redirect');
 
 $exception = $_SESSION['exception'] ?? null;
 $passwordRequired = false;
diff --git a/www/sessions/post.php b/www/sessions/post.php
index f17b90d6..ca51d714 100644
--- a/www/sessions/post.php
+++ b/www/sessions/post.php
@@ -12,9 +12,9 @@ session_start();
 $requestType = HttpInput::RequestType();
 
 $session = new Session();
-$email = HttpInput::Str(POST, 'email', false);
-$password = HttpInput::Str(POST, 'password', false);
-$redirect = HttpInput::Str(POST, 'redirect', false);
+$email = HttpInput::Str(POST, 'email');
+$password = HttpInput::Str(POST, 'password');
+$redirect = HttpInput::Str(POST, 'redirect');
 
 try{
 	if($redirect === null){