Error: "Invalid image or unsupported image format"

The error message "Invalid image or unsupported image format" can be sometimes puzzling, especially when the actual image exists and looks good when viewed in a browser.

Here are some of the usual reasons for this and possible solutions:

  • Images that actually have errors or simply don't exist in the server. To check if this is the case, just open the image file on a new tab and see if it can be displayed properly. A possible solution is to use a plugin like Enable Media Replace to re-upload and replace the images that are broken.
  • A firewall that prevents our servers to access your images. Please whitelist our IPs.
  • Restrictive rules in the ".htaccess" file. A quick way to check whether ".htaccess" is the reason for this issue is to temporary change the name of the file to -for example- ".htaccess_tmp" and then try again to see if the plugin can optimize a newly added image.
  • Wrong WordPress settings. Please check if the URL of your site is correctly set in Settings > General.
  • Unsupported image formats (e.g. .svg). Remember that ShortPixel Image Optimizer can only optimized JPG, PNG, GIF and PDF files.
  • You're using a security plugin that has an option that prevents the images from being properly accessed (e.g. "Long URL strings" option in the iThemes Security plugin).
  • Sometimes the images are not actually images. If that's the case, the website returns an HTML file with HTTP code 200 (which means "everything OK") but ShortPixel will fail to optimize. If you are sure the file you are trying to optimize is an image, in our experience usually this happens when there are some firewall restrictions in Cloudflare. Here is a guide on how to debug.

For other possible reasons, we'd recommend you to take a look at this article: None of my images were optimized, why is that?

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