SQL Error

[alleks111]

Sent, quoted a message, hung, reloaded the page, jumped out:

MyBB has experienced an internal SQL error and cannot continue.

SQL Error:1062 - Duplicate entry 'ac6ae13b8c86453210a237908dc3daf6' for key 'PRIMARY'Query:UPDATE c083_sessions SET sid='ac6ae13b8c86453210a237908dc3daf6', uid=22, time=1581495959, ip=X'4ad0eca1', location='/index.php' WHERE uid='22'

After a minute or two, the forum began to work normally again. Sent that message.
I go to another thread to answer. I click again to quote and everything repeats, after the forum works fine again.

What could it be?

[.m.]

probably it is a problem with recently added plugin / modified code (fake users online)

[alleks111]

I also suggested that because of this plugin.
Okay, now I’ll write it off to the author, then I will learn from him in more detail whether this forum will break me by the result.