[Error Message] Login / Logout not working

[rphro123]

Hello everyone, 

my website is http://www.bestincom.com/mybb/Upload/index.php I am not able to login or logout, When i login to site then I got the error authorization code mismatch or it just reloads without login, 
when I click on logout then nothing happens it just get back to the same page. 

cookies is fine my site setting, not sure what is the issue.

[.m.]

see => authorization code mismatch fixing guidance

[Mastersly]

usually it happent to me when i install a new theme
check this too
https://anonshare.eu/Thread-Tutorial-Can...all-themes

[Darth Apple]

MyBB has added more post code variables into its code to better secure it over the years. If you're getting this error, the theme has not been updated to use the latest version of MyBB.

This is very common, unfortunately. I experience these issues from time to time myself, but it is a side effect of MyBB becoming more secure in recent releases. If the theme was not released or updated for a relatively recent version of MyBB 1.8.x, most themes will require manual edits, as @m mentioned.