Error: "Invalid response from server"
The error message "Invalid response from server" can be sometimes puzzling, especially when the actual image exists and looks good when viewed in a browser.
If you receive this error, it might be that there is some output from another plugin (or some notice/warning) that corrupts the JSON answers of the AJAX calls of our plugin. To see this output, you can open the Developer Tools (usually F12, or Cmd-Opt-' on Mac) and
- Click on the Network tab
- Select the XHR filter
- Click on any admin-ajax.php request
- Select the Response tab
What you see here is the correct AJAX call:
If you don't see something similar, then we recommend you to try to find the conflicting plugin.
- Deactivate all plugins except ShortPixel
- Activate one by one the plugins. After each single activation, retry the bulk optimization until you find the plugin that corrupts the JSON responses.
For other possible reasons, we recommend you to take a look at this article: None of my images were optimized, why is that?