Confirm the user's homepage URL is correctly formatted to include the HTTP/HTTPS protocol in it.

Bug was fixed in UBB.threads 7.7.2 (Released July 2nd, 2019).
[FIX] CP: Fixed Member Editor not allowing updates due to Member Homepage URL not conforming with HTML5 input URL requirements.
https://www.ubbcentral.com/forums/ubbthreads.php/topics/262892/7-7-2-changelog-discussion

The current version of UBB.threads is 7.7.3 (Released July 28th, 2019).

Current developer of UBB.threads PHP Forum Software
Current Release: UBBT 7.7.5 // Preview: UBBT 8.0.0
isaac @ id242.com // my forum @ CelicaHobby.com