Failed to load resource: the server responded with a status of 500 (Internal Server Error)
1) If you have any security plugins installed then check to see whether they are blocking any specific file types
2) Check the “.htaccess” file in your WordPress root directory to see whether it is blocking all file types, like so:
Order deny,allow Deny from all
If so then you can add an exception to the file to allow the plugin to access the files it needs to load:
<Files ~ "query.php$|comments.php$|thumbs.php$"> Allow from all </Files>
If you’re not sure how to do this then you can contact your web host support team and ask them for assistance.
3) Ask your web hosting support team to check whether there’s anything on the server that is blocking those files.