I’m getting the error in the title and can’t regenerate images, not in bulk or just one image in the media library. The only thing that changed is that I just migrated from the Atomic Blocks plugin to the Genesis Blocks plugin. Also I now see that the featured image in my latest blog is not regenerated by the Genesis Grid plugin. I have no idea where the problem could be, just that the Regenerate Thumbnails plugin gives me that error message

You can see the not changed thumbail in the post Gismo:
https://www.jacktummers.nl/blog/