When you optimize an image with ShortPixel Image Optimizer, you may receive the message “Could not download file”.
There are two common reasons for this error:
1) Your website uses a firewall or security feature that prevents our Image Optimization Cloud from accessing your website’s images. Make sure you whitelist our IPs in your security plugins, firewalls, hosting, and/or CDN. In some cases, whitelisting IPs may not be enough, as some hosting services block the ports we need to access your images. We also recommend contacting your host and asking them to allow api.shortpixel.com access to port 80 (HTTP) and port 443 (HTTPS).
2) The image and/or its thumbnails are listed in the Media Library (and therefore exist in the database) but no longer exist physically on disk. To check this, download your Optimization Report from this page and search for the image in question. Once you find it, you will also see the thumbnails. Copy the URL of each image or thumbnail and open it in an Incognito/Private browser window to identify which image is missing or inaccessible. For example:
