Teachers want to disable the download option of some files like audio,video files . They want students to only view these files . So the teacher want to disable download of some files , not all . Please help .

it's not possible in the core Files plugin. You could develop a plugin that adds an option on the file form to control if download is available.

If disabled, don't register (or remove) the download button.

This requires some development, but it can be done.

I believe that disabling the download of image files, audio files or video files is actually useless because if the user can access and view these files, they can always obtain a copy of an image (screenshot), a copy of a video (screen recording) or a copy of an audio (audio recording).

I suggest you use 'Developer tools' plugin to find the error instead of digging through the error log.

1 - Go to 'Plugins' page and activate 'Developer tools' plugin.

2 - Go to the plugin's settings page /admin/plugin_settings/developers

3 - Select 'Trace level' option and choose 'Log errors and warnings'

4 - Switch on 'Enable error log' option and 'Save' settings

5 - Now reproduce your critical error and check out log on the /admin/develop_tools/error_log page

Nikolai,  I can't go to the page because the error doesn't allow me to see the login page. However, if you tell me how to activate that plugin from the server side, I could edit it and maybe get results.

"Fatal error in exception handler. Check log for Exception at time 1751315922  " is all I see from the browser side".
Thank You.

This error was fixed by Optimizing Tables on the website's database. Also, it happened because o high use of memory.
Thank You.

You need to unregister 'register', 'menu:filter:filter' event and register a new event in your custom plugin:

'menu:filter:filter' => [
    'Elgg\Menus\Filter::registerFilterTabs' => ['unregister' => true],
    'MyPlugin\Menus\Filter::registerFilterTabs' => [],
],

Thank you very much for your response.
I was hoping there was a single file ("filter.php", for example) that I could easily copy and modify.

I see the solution isn't as easy as I thought.

Thank you very much, again.

Best regards.