I believe others also have highlighted this issue. I get this error off and on when I am trying to comment or reply to comments on drama's pages. But for the first time today I got this error while using the forums.
Usually if I type a reply and post in the comments section, I will refresh the page if I get the error and my comment would have been posted so I managed to avoid posting twice.
But on the forums, I hit reply twice just in case and when I refreshed the page, nothing had been posted. Just wanted to bring this error to the attention of the staff.
I've also tried logging out and back in but it didn't resolve the error. I use Brave browser.