Limitation of resources
This type of error usually occurs with websites hosted on shared hosting solutions. Such hostings usually have a certain number of CPU threads that can run in parallel, and when this limit is reached, ShortPixel returns such “Internal Server Error” messages.
Here are the common steps to fix this problem:
- Make sure you are not already running a CPU or disk intensive task like creating a backup of your website. If you are running such a resource-intensive task, just wait for it to finish before trying to run the image optimization again.
- Check your plugins and see if you have 2-3 plugins that you can temporarily deactivate. Once you have them deactivated, simply try running ShortPixel Image Optimizer again. In most cases, this will free up enough CPU resources to finish optimizing the images on your site.
If this does not help,
please contact your hosting provider so that they can assist you further.
Multisite
If you are running a multisite, you will sometimes see this or a similar message:
Error: There was an error and your request was not processed. (20190603_190924.jpg: Could not download file (500 Internal Server Error).)
The error may be related to upload paths. When you upload to a subdomain (if you have configured the secondary site in a WordPress multisite as a subdomain), the upload path in the multisite’s database (it is a single database) is still set to the main site by default. This means that the images don’t appear in the subdomain’s media library (only when you click on them to edit them, but that makes no difference) and that the subdomain has not been told how to “download” the images from the main site’s upload path.
The possible solution is to access the database, look for ‘upload path’ in the
options table and change it. This is what you will probably see:
/var/sites/a/yourdomain.com/public_html/wp-content/uploads
Change it to…
wp-content/uploads
…and it should work. Both the main and the subdomain can access this path.