thom_s

I realized it was a problem with db-prefix. I was also testing a special wp-config configuration, https://gist.github.com/ashfame/1923821, where I put a local and dev config a folder above the “standard” config.
I had not renamed the prefix in the local config, as I had a differrent prefix on the devsite. When I put the same prefix in both config files, everything worked fine.

I had exactly the same problem, found an answer that worked in this post: change permissions on the folder wp-content to 766…

…and changing the permissions back to 755 made it work so I could both click the button and see the pictures.

All this happened after trying to make a automated upgrade for the first (and last) time.