Has anyone actually managed to successfully upgrade?
I tried myself yesterday and had multiple issues resulting in a unusable WHMCS installation, had to restore from backup to get things running properly again.
Sounds like the update has pulled the rug out from under 3rd party developers feet also. I run JWHMCS and it looks like they have had to scramble to try and adapt their adons to work with 5.2.1. (your efforts are much appreciated btw).
I would mutch rather a thoroughly tested stable product rather than the latest bells and whistles, this is a billing platform after all, stability is key.
Depending on how widespread the upgrade problems are I would suggest pulling the 5.2.1 download untill its fixed (sounds like whmcs have a backlog of support tickets to deal with so would give them a chance to catch up on that too!).
Seriously not impressed.
