diff --git a/MDErrorReporter.php b/MDErrorReporter.php
index 4c920e6..02ed982 100644
--- a/MDErrorReporter.php
+++ b/MDErrorReporter.php
@@ -7,7 +7,7 @@ declare(strict_types = 1);
 /**
  * Debugging and error handling class.
  */
-class MDErrorReporter {
+final class MDErrorReporter {
 
     const MD_ERROR_UNKNOWN  = 20;
     const MD_ERROR_CRITICAL = 10;
diff --git a/exceptions/generic/MDAccessDeniedException.php b/exceptions/generic/MDAccessDeniedException.php
index 4c8e93f..944aabb 100644
--- a/exceptions/generic/MDAccessDeniedException.php
+++ b/exceptions/generic/MDAccessDeniedException.php
@@ -4,7 +4,7 @@ declare(strict_types = 1);
 /**
  * Custom exception class for invalid page parameters.
  */
-class MDAccessDeniedException extends MDExpectedException {
+final class MDAccessDeniedException extends MDExpectedException {
 
     /**
      * Error message.
diff --git a/exceptions/generic/MDConfigCannotBeLoadedException.php b/exceptions/generic/MDConfigCannotBeLoadedException.php
index 8b847f8..d7a33b0 100644
--- a/exceptions/generic/MDConfigCannotBeLoadedException.php
+++ b/exceptions/generic/MDConfigCannotBeLoadedException.php
@@ -4,7 +4,7 @@ declare(strict_types = 1);
 /**
  * Custom exception class for errors loading configuration information.
  */
-class MDConfigCannotBeLoadedException extends Exception {
+final class MDConfigCannotBeLoadedException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/generic/MDFileDoesNotExist.php b/exceptions/generic/MDFileDoesNotExist.php
index 154fb4f..d6d8fb5 100644
--- a/exceptions/generic/MDFileDoesNotExist.php
+++ b/exceptions/generic/MDFileDoesNotExist.php
@@ -2,8 +2,6 @@
 /**
  * This file contains an exception class for trying to enter non-existent files.
  *
- * @file
- *
  * @author Joshua Ramon Enslin <joshua@museum-digital.de>
  */
 declare(strict_types = 1);
@@ -11,7 +9,7 @@ declare(strict_types = 1);
 /**
  * Custom exception class for non-existing files.
  */
-class MDFileDoesNotExist extends Exception {
+final class MDFileDoesNotExist extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/generic/MDFileIsNotReadable.php b/exceptions/generic/MDFileIsNotReadable.php
index 8d9f82b..55b0319 100644
--- a/exceptions/generic/MDFileIsNotReadable.php
+++ b/exceptions/generic/MDFileIsNotReadable.php
@@ -2,8 +2,6 @@
 /**
  * This file contains an exception class for trying to enter non-existent files.
  *
- * @file
- *
  * @author Joshua Ramon Enslin <joshua@museum-digital.de>
  */
 declare(strict_types = 1);
@@ -11,7 +9,7 @@ declare(strict_types = 1);
 /**
  * Custom exception class for non-existing files.
  */
-class MDFileIsNotReadable extends Exception {
+final class MDFileIsNotReadable extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/generic/MDInaccessiblePropertyException.php b/exceptions/generic/MDInaccessiblePropertyException.php
index bdba6fd..ba22492 100644
--- a/exceptions/generic/MDInaccessiblePropertyException.php
+++ b/exceptions/generic/MDInaccessiblePropertyException.php
@@ -4,7 +4,7 @@ declare(strict_types = 1);
 /**
  * Custom exception class for errors loading configuration information.
  */
-class MDInaccessiblePropertyException extends Exception {
+final class MDInaccessiblePropertyException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/generic/MDOutputBufferNotStarted.php b/exceptions/generic/MDOutputBufferNotStarted.php
index 38f7567..c5f3f1a 100644
--- a/exceptions/generic/MDOutputBufferNotStarted.php
+++ b/exceptions/generic/MDOutputBufferNotStarted.php
@@ -2,8 +2,6 @@
 /**
  * This file contains an exception class for trying to enter non-existent files.
  *
- * @file
- *
  * @author Joshua Ramon Enslin <joshua@museum-digital.de>
  */
 declare(strict_types = 1);
@@ -11,7 +9,7 @@ declare(strict_types = 1);
 /**
  * Custom exception class for non-existing files.
  */
-class MDOutputBufferNotStarted extends Exception {
+final class MDOutputBufferNotStarted extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/generic/MDRequiredConfigNotSet.php b/exceptions/generic/MDRequiredConfigNotSet.php
index 7dd5450..6fadc46 100644
--- a/exceptions/generic/MDRequiredConfigNotSet.php
+++ b/exceptions/generic/MDRequiredConfigNotSet.php
@@ -4,7 +4,7 @@ declare(strict_types = 1);
 /**
  * Custom exception class for errors loading configuration information.
  */
-class MDRequiredConfigNotSet extends Exception {
+final class MDRequiredConfigNotSet extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/generic/MDhttpFailedException.php b/exceptions/generic/MDhttpFailedException.php
index 32e1be6..3b49773 100644
--- a/exceptions/generic/MDhttpFailedException.php
+++ b/exceptions/generic/MDhttpFailedException.php
@@ -5,7 +5,7 @@ declare(strict_types = 1);
  * Exception thrown in case the main entity of a page (e.g. an object, an institution etc.)
  * are not set public.
  */
-class MDhttpFailedException extends Exception {
+final class MDhttpFailedException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/generic/MDmainEntityNotExistentException.php b/exceptions/generic/MDmainEntityNotExistentException.php
index 59e9b6f..f8912c7 100644
--- a/exceptions/generic/MDmainEntityNotExistentException.php
+++ b/exceptions/generic/MDmainEntityNotExistentException.php
@@ -5,7 +5,7 @@ declare(strict_types = 1);
  * Custom exception class for invalid page parameters, which must be values of a
  * preset list of allowed values.
  */
-class MDmainEntityNotExistentException extends Exception {
+final class MDmainEntityNotExistentException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/generic/MDpageParameterNotFromListException.php b/exceptions/generic/MDpageParameterNotFromListException.php
index c5f54fe..4d4fc00 100644
--- a/exceptions/generic/MDpageParameterNotFromListException.php
+++ b/exceptions/generic/MDpageParameterNotFromListException.php
@@ -5,7 +5,7 @@ declare(strict_types = 1);
  * Custom exception class for invalid page parameters, which must be values of a
  * preset list of allowed values.
  */
-class MDpageParameterNotFromListException extends Exception {
+final class MDpageParameterNotFromListException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/page/MDPageNotInAggregatedException.php b/exceptions/page/MDPageNotInAggregatedException.php
index 7073511..e6da3b7 100644
--- a/exceptions/page/MDPageNotInAggregatedException.php
+++ b/exceptions/page/MDPageNotInAggregatedException.php
@@ -5,7 +5,7 @@ declare(strict_types = 1);
  * Exception thrown in case the main entity of a page (e.g. an object, an institution etc.)
  * are not set public.
  */
-class MDPageNotInAggregatedException extends Exception {
+final class MDPageNotInAggregatedException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/page/MDmainEntityNotPublicException.php b/exceptions/page/MDmainEntityNotPublicException.php
index a7465b3..dd44032 100644
--- a/exceptions/page/MDmainEntityNotPublicException.php
+++ b/exceptions/page/MDmainEntityNotPublicException.php
@@ -5,7 +5,7 @@ declare(strict_types = 1);
  * Exception thrown in case the main entity of a page (e.g. an object, an institution etc.)
  * are not set public.
  */
-class MDmainEntityNotPublicException extends Exception {
+final class MDmainEntityNotPublicException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/page/MDpageParameterMissingException.php b/exceptions/page/MDpageParameterMissingException.php
index 40c97f9..bd9364c 100644
--- a/exceptions/page/MDpageParameterMissingException.php
+++ b/exceptions/page/MDpageParameterMissingException.php
@@ -4,7 +4,7 @@ declare(strict_types = 1);
 /**
  * Custom exception class for missing page parameters.
  */
-class MDpageParameterMissingException extends Exception {
+final class MDpageParameterMissingException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/page/MDpageParameterNotNumericException.php b/exceptions/page/MDpageParameterNotNumericException.php
index 0d8346a..a052185 100644
--- a/exceptions/page/MDpageParameterNotNumericException.php
+++ b/exceptions/page/MDpageParameterNotNumericException.php
@@ -4,7 +4,7 @@ declare(strict_types = 1);
 /**
  * Custom exception class for invalid page parameters.
  */
-class MDpageParameterNotNumericException extends Exception {
+final class MDpageParameterNotNumericException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDDuplicateLinkException.php b/exceptions/updates/MDDuplicateLinkException.php
index 90bb90e..6239a8d 100644
--- a/exceptions/updates/MDDuplicateLinkException.php
+++ b/exceptions/updates/MDDuplicateLinkException.php
@@ -5,7 +5,7 @@ declare(strict_types = 1);
  * Exception thrown in case an erroneously duplicate link is to be entered in a
  * linking table.
  */
-class MDDuplicateLinkException extends Exception {
+final class MDDuplicateLinkException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDFileUploadNotAcceptedException.php b/exceptions/updates/MDFileUploadNotAcceptedException.php
index 82a91b5..84f1054 100644
--- a/exceptions/updates/MDFileUploadNotAcceptedException.php
+++ b/exceptions/updates/MDFileUploadNotAcceptedException.php
@@ -5,7 +5,7 @@ declare(strict_types = 1);
  * Custom exception class for invalid page parameters, which must be values of a
  * preset list of allowed values.
  */
-class MDFileUploadNotAcceptedException extends Exception {
+final class MDFileUploadNotAcceptedException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDInvalidCurrency.php b/exceptions/updates/MDInvalidCurrency.php
index 35c2356..8443e6e 100644
--- a/exceptions/updates/MDInvalidCurrency.php
+++ b/exceptions/updates/MDInvalidCurrency.php
@@ -12,7 +12,7 @@ declare(strict_types = 1);
  * Custom exception class to be raised when trying to use a currency that is not
  * accepted by museum-digital.
  */
-class MDInvalidCurrency extends MDgenericInvalidInputsException {
+final class MDInvalidCurrency extends MDgenericInvalidInputsException {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDInvalidInputDate.php b/exceptions/updates/MDInvalidInputDate.php
index 37a8193..975e629 100644
--- a/exceptions/updates/MDInvalidInputDate.php
+++ b/exceptions/updates/MDInvalidInputDate.php
@@ -12,7 +12,7 @@ declare(strict_types = 1);
  * Custom exception class to be raised when trying to use a currency that is not
  * accepted by museum-digital.
  */
-class MDInvalidInputDate extends Exception {
+final class MDInvalidInputDate extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDInvalidLengthUnit.php b/exceptions/updates/MDInvalidLengthUnit.php
index 037d3f1..63db37a 100644
--- a/exceptions/updates/MDInvalidLengthUnit.php
+++ b/exceptions/updates/MDInvalidLengthUnit.php
@@ -12,7 +12,7 @@ declare(strict_types = 1);
  * Custom exception class to be raised when trying to use a length unit that is not
  * accepted by museum-digital.
  */
-class MDInvalidLengthUnit extends MDgenericInvalidInputsException {
+final class MDInvalidLengthUnit extends MDgenericInvalidInputsException {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDInvalidLicense.php b/exceptions/updates/MDInvalidLicense.php
index 8b03d55..68f2f95 100644
--- a/exceptions/updates/MDInvalidLicense.php
+++ b/exceptions/updates/MDInvalidLicense.php
@@ -12,7 +12,7 @@ declare(strict_types = 1);
  * Custom exception class to be raised when trying to use a license that is not
  * accepted by museum-digital.
  */
-class MDInvalidLicense extends MDgenericInvalidInputsException {
+final class MDInvalidLicense extends MDgenericInvalidInputsException {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDInvalidObjectPublicationBackground.php b/exceptions/updates/MDInvalidObjectPublicationBackground.php
index 20822d3..e6e052d 100644
--- a/exceptions/updates/MDInvalidObjectPublicationBackground.php
+++ b/exceptions/updates/MDInvalidObjectPublicationBackground.php
@@ -12,7 +12,7 @@ declare(strict_types = 1);
  * Custom exception class to be raised when trying to use a license that is not
  * accepted by museum-digital.
  */
-class MDInvalidObjectPublicationBackground extends MDgenericInvalidInputsException {
+final class MDInvalidObjectPublicationBackground extends MDgenericInvalidInputsException {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDInvalidWeightUnit.php b/exceptions/updates/MDInvalidWeightUnit.php
index 584d63b..cd18927 100644
--- a/exceptions/updates/MDInvalidWeightUnit.php
+++ b/exceptions/updates/MDInvalidWeightUnit.php
@@ -12,7 +12,7 @@ declare(strict_types = 1);
  * Custom exception class to be raised when trying to use a weight unit that is not
  * accepted by museum-digital.
  */
-class MDInvalidWeightUnit extends MDgenericInvalidInputsException {
+final class MDInvalidWeightUnit extends MDgenericInvalidInputsException {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDNoUpdateVarSetException.php b/exceptions/updates/MDNoUpdateVarSetException.php
index 6a73260..55f5da6 100644
--- a/exceptions/updates/MDNoUpdateVarSetException.php
+++ b/exceptions/updates/MDNoUpdateVarSetException.php
@@ -5,7 +5,7 @@ declare(strict_types = 1);
  * Custom exception class for invalid page parameters, which must be values of a
  * preset list of allowed values.
  */
-class MDNoUpdateVarSetException extends Exception {
+final class MDNoUpdateVarSetException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDTooManyFilesUploadException.php b/exceptions/updates/MDTooManyFilesUploadException.php
index 75c9db1..1c80829 100644
--- a/exceptions/updates/MDTooManyFilesUploadException.php
+++ b/exceptions/updates/MDTooManyFilesUploadException.php
@@ -11,7 +11,7 @@ declare(strict_types = 1);
 /**
  * Custom exception class for wrongly used files.
  */
-class MDTooManyFilesUploadException extends Exception {
+final class MDTooManyFilesUploadException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDWrongFileType.php b/exceptions/updates/MDWrongFileType.php
index 38a4049..b487646 100644
--- a/exceptions/updates/MDWrongFileType.php
+++ b/exceptions/updates/MDWrongFileType.php
@@ -11,7 +11,7 @@ declare(strict_types = 1);
 /**
  * Custom exception class for wrongly used files.
  */
-class MDWrongFileType extends Exception {
+final class MDWrongFileType extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDcouldNotSaveException.php b/exceptions/updates/MDcouldNotSaveException.php
index 9c086fc..854ea41 100644
--- a/exceptions/updates/MDcouldNotSaveException.php
+++ b/exceptions/updates/MDcouldNotSaveException.php
@@ -5,7 +5,7 @@ declare(strict_types = 1);
  * Exception thrown in case the main entity of a page (e.g. an object, an institution etc.)
  * are not set public.
  */
-class MDcouldNotSaveException extends Exception {
+final class MDcouldNotSaveException extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDcouldNotSetPublic.php b/exceptions/updates/MDcouldNotSetPublic.php
index 468a64b..43e6d7c 100644
--- a/exceptions/updates/MDcouldNotSetPublic.php
+++ b/exceptions/updates/MDcouldNotSetPublic.php
@@ -5,7 +5,7 @@ declare(strict_types = 1);
  * Exception thrown in case the main entity of a page (e.g. an object, an institution etc.)
  * are not set public.
  */
-class MDcouldNotSetPublic extends Exception {
+final class MDcouldNotSetPublic extends Exception {
 
     /**
      * Error message.
diff --git a/exceptions/updates/MDwriteAccessDeniedException.php b/exceptions/updates/MDwriteAccessDeniedException.php
index 61706d6..adbcc87 100644
--- a/exceptions/updates/MDwriteAccessDeniedException.php
+++ b/exceptions/updates/MDwriteAccessDeniedException.php
@@ -5,7 +5,7 @@ declare(strict_types = 1);
  * Exception thrown in case the main entity of a page (e.g. an object, an institution etc.)
  * are not set public.
  */
-class MDwriteAccessDeniedException extends Exception {
+final class MDwriteAccessDeniedException extends Exception {
 
     /**
      * Error message.