This is a repeating behavior of odoo forum page, I asked the same before and I didn't get a  proper response. We are facing the same issues while trying to edit our answers or converting comment to answers.

See my prev question here

https://www.odoo.com/forum/help-1/question/400-bad-request-on-odoo-forum-118289

While I am trying to answer the same I am getting the same response.

https://www.odoo.com/forum/help-1/question/meta-issue-error-with-forum-when-posting-answer-403-forbidden-400-bad-request-error-130171