Hi,
My website has been rendered non-operational. I went to update a banner and after I uploaded it I pressed "set as feature image" and this pop up appeared:
Could not set as the thumbnail image. Try a different attachment
This is something I do all the time so I'm not sure what has changed? I have read other threads but I'm still none the wiser. I have disabled all my plugins and it still doesn't work. I've read somewhere that people are "repairing their database". How do I do this and will it work?