ShortPixel guide to HTTP error codes

error codes

We hope that nobody will have to read this article. But if you are here, this means that you have a problem with our online service, and you got a three figure code that should explain your issue.

Please read further to find what you need to do if you get a HTTP status error when you are using ShortPixel.

ShortPixel optimize images in the cloud. It takes user’s images to our servers, where they are compressed, and it copies their smaller version back to your site. For this operation to be successful, our servers need to contact your site.

Important: If your site is being locally hosted , then our service will not work.

The most common HTTP status errors

We don’t include all HTTP status codes in this article, only those that could occur when ShortPixel cannot work properly. For a complete list of error codes you could check these sources: Wikipedia,,

401 HTTP status error: Unauthorized access

When: You get these error if the images are stored in a password protected folder.

Solution: Please go to the ShortPixel plugin settings, click on Advanced tab, and scroll down until you find the HTTP Auth field. Add your credentials there and save the settings.

Note: Please don’t confuse these credentials with those needed for logging to your WordPress admin dashboard.

403 HTTP status error: Forbidden access

When: Similar with 401 error, 403 error is an access type error. It is displayed when the credentials used in HTTP Auth field are wrong.

Solution: Please check that you used the right login/password info in the HTTP Auth field from the ShortPixel settings menu.

Note: Some servers are setup to return 404 instead of 403, because the site administrator doesn’t want to disclose that the reason of the error.

404 HTTP Status error: Not Found

When: Anytime a resource/page is not found at the requested URI the server returns 404 status.

If you got this error when you try to optimize image/s with ShortPixel then most likely:
– the images were removed from the server,
– or they were moved to other location from the server, without updating the WP metadata accordingly.
– the images are stored locally.

Solution: Unfortunately, ShortPixel can compress only images that are publicly accessible. Please re-upload the missing images.

A common approach for all those 5XX errors:

You cannot do much about the 5XX errors because they are related to your server. In our intention to help, we can investigate for you the issue and advise you how to proceed. To get our help, you have to contact our support team.

You can also wait and try to resume the optimization after a few hours. Knowing the issue we have set up alerts that announce us when servers have issues.

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