Windows Client will not register

[Shiggins88]

I recently upgraded 3CX v14 to v15.5. I have sketchy 3CX Windows client behavior on some of our workstations. It says:

This client is not compatible with the current version of 3CX phone system version 15.5 updated with the current version of 3CX phone system version 15.5 updated with the latest service pack is required.

It works on some but not others

 

[Shiggins88]

Just tried your suggestion after an uninstall, deleting both folders, restarted and reinstalled. Unfortunately it is still saying the same thing.