Hello,
I’m trying to merge two topics together. I select the topic to merge into, press the submit button, then an empty page opens with the message “A variable mismatch has been detected”.

I’m using
Wordpress 5.3.2
bbPress 2.6.3
on my site http://www.renegadeskutr.cz/forums/forum/srazy-a-akce/

I also tried editing a topic, pinning/unpinning, etc. and these functions work properly.

It seems this is a common issue with many plugins since WordPress 5.0.1. I googled and found many topics with the same issue from other plugins. Apparently “WordPress checks if GET and POST inputs match and, in case of mismatch, it throws the error.”
https://wordpress.org/support/topic/a-variable-mismatch-has-been-detected-6/page/4/

How can I fix the problem?

[@domeboys Participant 4 years, 10 months ago]

I have the same problem (variable mismatch message when trying to merge forum topics) and would appreciate resolution advice. Thanks.

This problem is relatively new for me, as the function had worked fine for several years until the last few months.

WP 5.3.2
PHP 7.3.14
bbPress 2.6.4