[Error Message] authorization code mismatch

[Seaark]

I am using MyBB version  1.8.26.  Everything was going well without any problems until Hostmonster upgrade to PHP version 7.4.18.  Now I am getting Authorization code mismatch. Are you accessing this function correctly? Please go back and try again.  

Everything I read on the subject is dated.  Nothing about this problem in 2021.   I check the files mentioned in the dated material but that does not seem to be my problem.   Does anyone have an idea how to fix this problem.  Thank you.

[noyle]

My guess: your hosting might have switched on some cache mechanism so your MyBB forum may get same IP for user visits.

Try this to see if the problem will go away:
enable the following setting: Admin CP -> Configuration -> Settings -> Server and Optimization Options -> Scrutinize User's IP address?

Please report back if this option is already turned on or by turning it on the problem persists.

[Seaark]

Thanks but Scrutinize User's IP address had no effect. I still get the error when I try to log in.