I thought that since I just installed a new theme, perhaps the theme was causing a problem. Reverted to the old theme, but still had the upload problem. Tried the twenty twelve theme, just in case. No go. I even tried a different browser, though I had no reason to think that would work. It didn’t. I’ve tried deactivating all the plugins, since that often helps with problems. That didn’t work. I’ve also updated all the plugins. That didn’t work either. Not sure where to go from here, except to pick a theme that doesn’t use a background image so I don’t need to upload anything at this time, which seems like a pretty bad solution.
Try contacting your hosts and asking them to check if you have a folder ownership issue.
Thanks. I’ve just put in a ticket with them.
In case this happens to anyone else: the filepath setup in my WordPress under Settings > Media was wrong. This must have worked at one time, because there was an image in the media library. I believe it got changed in upgrades my host did a while back, and I missed this site when making necessary changes. This now works, with the wp-content, upload, etc. directories set to 755.
tery93 – Thank you so very much! I recently changed servers and since then have been getting the error message discussed. Found lots of suggestions over the Internet, none of which worked. Found yours, corrected the filepath setup (which was still going to my old server) and everything’s working perfectly again. I appreciate your sharing the solution here and am grateful to you!