After delaying upgrade to 13.0 from 12.2 for months, I decided to skip and upgrade directly to 13.1. I have upgraded 3-4 times before so I thought I knew the drill. The fact is that after upgrading I am unable to edit any wiki page: The edit page opens but the edit window is blank and I am unable to do anything into it. Also, I don't see the editor buttons etc. The strange thing is that I can edit articles. Next... strange thing: Some windows appear blank as well (for example, the "I forgot my password" window is blank and you can't type anything there) while others appear ok (for example, the "contact us" window, where you can type). What could be the reason for different windows acting in different ways? Don't know.
After all this, I decide to try, instead of upgrading, a clean install and db import. I got exactly the same problem. Edit wiki page window is a... white winter blanket, edit article is fine etc.
The only thing I could report is that while connecting with db I got 5 error messages (in both cases, upgrade/clean install), which I thought was not serious and continued anyway. I don't remember now what the errors were, though. If important, surely I can try another another install and write down the error messages.
Any thoughts before I try my luck again?
PS that might be important: Until yesterday, my host server was using php 5.3.X.
I asked and got an upgrade to 5.5.X (as the tiki 13.1 demands) just before upgrading my wiki.
PS 2. Picture shows the blank window. Even then, preview works ok.