It seems that there is a problem with text file editing after updating to NC 12.0.3. Even if I deactivate Note.app, it is the same.
Error PHP call_user_func() expects parameter 1 to be a valid callback, class 'OCA\Richdocuments\Storage' not found at /NEXTCLOUD DIRECTORY/lib/private/legacy/hook.php#106
Error files_texteditor File: /Notes/SAMPLE.txt modified since opening.
These errors occur 100% when operating this file.
Because I was able to open a text file already saved and saved, it seems not to be a fatal problem .
This error didn’t occur in 12.0.2.
CentOS 7.3 / nginx 1.11.13 / PHP 7.1.9 / NC 12.0.3