is it a bug?

it hapoened when trying to send mail to a user by clicking send mail.

i saw the message i tried to send underthe text invalid security token. i was not able to do anything on that page , the only action i could take was going back to previous page by pressing back on my keyboard.

i have no ad block and cookies are enabled on my device , so i do not know any possible reason this happened.

how does a security token become invalid on gelbooru?

i never knew that security tokens even existed before this hapoened to me.

possible gelbooru/booru imageboard site bug/trouble shooting issue.

i tried sending that same message after pressing the back button on my keyboard and it went through and it was sent.

it only happened once from the time i staryed using gelbooru , which was today.
i do not know what any of this means , so i thought to bring it up here.

maybe this could be a rare minor glitch in the booru imaGeboards?

i have not seen other websites talk about something like this before , this could be the first time it ever happened?

We generate a security token before post requests are made to the site. Sometimes your previous token expires before you can send a message, or a race condition occurred making it so you didn't have a token at all before the message was sent. The only solution is to refresh the page you were on before sending the comment/edit/pm.

I get this all the time too. Why does everything have to be so complicated???

Blame PHP being finicky (as always) and people trying to carry out CSRF (cross-site request forgery) attacks against the site. No offense to you, @umknown.