[@jkuzma Participant 10 years, 5 months ago]

Most likely all the above replies which are *not* the same thing, they are all different errors are caused by the same thing though, a plugin or theme conflict.

Yes, a BBPress conflict, because this issue did not exist prior to updating yesterday (May 2nd.)

This is a problem on the backend, and is not theme or plugin dependent, as I’m seeing it on more than one site. I have even reverted back to the previous version of BBPress, changed my PHP version, etc.

I get this error anytime I am editing/updating a post/page on the backend. The post/page will end up saving, but the errors popup, sometimes with wp-includes/pluggable.php as well (which I’ve also replaced.)

I’ve also gone through the tedious process of uninstalling and reinstalling every plugin on my site. It’s quite obvious that disabling only BBPress fixes the problem, which is not a solution by any means.