Question Error in adding media type

I am trying to add a .pdf as a media type and get the following error when I try to save it

SyntaxError: Unexpected token '<', "
Using version Website 2.2.6

I'm not sure what you have done exactly. Is there a stacktrace with that error message? Have you changed some code? Can you share a screenprint?

I don't think you've done the right thing. In webtrees the media type describes the type of content, not the file extention. For example the media type "picture" can be used with file extensions .png, .jpg. .bmp, etc etc, including .pdf

The .pdf file extension is already supported as a "mime type".
See github.com/fisharebest/webtrees/blob/7ed...fbb/app/Mime.php#L55

When adding a .pdf as a media object, I'd suggest "document" or "electronic" as the media type. The values are defined here:
github.com/fisharebest/webtrees/blob/7ed...rceMediaType.php#L80

The reason for that error message is that webtrees delivers JSON when html is expected. But the reason behind that is not clear. 

Good thinking, Hermann!
Here's a short guide to analyse with your web browser what has happened.
webtrees.net/faq/xhr/
Although this might not have been an XHR request, the method to see request & response details is similar.

It could be that the .pdf was too large.
webtrees.net/faq/file-upload/

I get same with a .jpg ... (possibly Cloudflare error?)

No, that is not related to Cloudflare, the reason is in webtrees. Please, deactivate your custom modules as a first step. For example rename the folder modules_v4 to modules_v9, then test again.

After renaming Models_v4 per your instructions, I still get the same error message: SyntaxError: Unexpected token '<', "

Well, I tested uploading some random image to your site, and that worked. So it's either something in this specific image, or it's the network route.

You can use the webtrees demo site (login with 'editor' - 'editor') to test uploading there. Or I can test it with your specific image on your site if you send it to me. Maybe I spot something you missed...

I cancelled CloudFlare, and everything is back to normal. Now I need to deal with the bots.