Problem creating Video Thumbnails

[tante]

We run Wordpress 6.3 with PHP 7.4.3-4ubuntu2.19.

There's an issue when trying to set a thumbnail. I can generate them (I get 4 suggestions from the video) but when trying to save them I get an "Internal Server Error".

The logs show:

[Tue Aug 22 13:18:00.804074 2023] [php7:error] [pid 144111] [client 80.82.201.37:56447] PHP Fatal error:  Uncaught Error: Call to a member function get_size() on bool in PATH_TO_WORDPRESS/wp-content/plugins/video-embed-thumbnail-generator-4.8.11/src/admin/videopack-admin-ajax.php:398
Stack trace:
#0 PATH_TO_WORDPRESS/wp-includes/class-wp-hook.php(310): kgvid_ajax_save_html5_thumb()
#1 PATH_TO_WORDPRESS/wp-includes/class-wp-hook.php(334): WP_Hook->apply_filters()
#2 PATH_TO_WORDPRESS/wp-includes/plugin.php(517): WP_Hook->do_action()
#3 PATH_TO_WORDPRESS/wp-admin/admin-ajax.php(188): do_action()
#4 {main}
thrown in PATH_TO_WORDPRESS/wp-content/plugins/video-embed-thumbnail-generator-4.8.11/src/admin/videopack-admin-ajax.php on line 398, referer: https://MYSITE/wp-admin/upload.php?item=7252

The problem seems to be in line 385: $editor = kgvid_decode_base64_png( $raw_png, $tmp_posterpath );

This does not seem to return an object.

[kylegilman]

Are you getting any specific errors in the Developer Console in your browser? It sounds like something is stopping the thumbnail from uploading to your server from your browser.

[tante]

Only the error that gets propagated from the backend upon trying to set one of the 4 generated images as thumbnail:

[tante]

Tested with a different browser (first was Chrome, now Firefox): Same problem. Looks like it's an issue server side? But other uploads (like uploading images or videos to the media library) work without problems.

[tante]

I have the same issue when setting an already existing image from the media gallery btw.

[kylegilman]

Ok, I can see where my bad error handling is causing a problem, but I can't tell exactly why the error is being generated. My best guess is it comes from PHP not having direct write access to the WordPress Media Library uploads folder. Have you made any changes to the location of the uploads folder?

[tante]

Nope, the Uploads folder is standard and the webserver has all rights to put things there (uploads in general work)