acdejong Hello,
It looks like the issue is related to the thumbnail resize feature. Could you please try temporarily disabling the Resize Thumbnail option in the JA Content Listing module and see if the error persists?
If the error no longer appears, it’s likely that the server’s PHP installation lacks WebP support in the GD library. In such cases, functions like imagecreatefromwebp() or imagewebp() will fail. You may want to check with your hosting provider to confirm whether WebP support is enabled.
Best regards
