Me too, tried different themes too. It doesn’t specify the error, just tells me to “try again later” when I try to upload a featured image. When I just click “set featured image” the library box pops up and is stuck on the loading screen. I go into the media folder from the dashboard and everything is there, it just won’t connect to posts and pages.
This was happening right before I upgraded to 4.0, and I hoped that upgrading would help… but no change.
I even changed hosting companies (moved to Bluehost) and the problem persists. Wish I knew what was up!
