By kim.pepper on
Change record status: 
Published (View all published change records)
Project: 
Drupal core
Introduced in branch: 
10.3.x
Introduced in version: 
10.3.2
Issue links: 
https://www.drupal.org/node/3156672
Description: 

\Drupal\Core\File\MimeType\ExtensionMimeTypeGuesser::guessMimeType() no longer returns a default of 'application/octet-stream' and returns NULL allowing other mime type guessers to try and guess the mime type. Instead Drupal\Core\File\MimeType\MimeTypeGuesser::guessMimeType() which gets called via \Drupal::service('file.mime_type.guesser')->guessMimeType() provides a default value of 'application/octet-stream'.

This allows other mime type guessers such as \Symfony\Component\Mime\FileBinaryMimeTypeGuesser to be added after ExtensionMimeTypeGuesser.

Impacts: 
Site builders, administrators, editors
Module developers
Site templates, recipes and distribution developers