http is stateless, meaning it once the webpage is downloaded, the website totally forgets who you are (which is why cookies exist).
Click the log out button.
close the browser window(s), reopen and go back to the website. if you're still logged in, clear your cookie cache.
Well DUH!!! Ofc http is stateless, that's a blindingly obvious statement to make on a developer forum. We rid ourselves of the clueless Lusers (copywrite alt.sysadmin.recovery) with the move ;) so its no longer necessary to assume people here are clueless.
However that does not in any way impact on what I said. It is obvious that the forum persists state info as otherwise you would have to log in again on every click, so it must be using session cookies.
Now without delving into the contents of the cookie I was merely stating that the error most commonly occurs after a lengthy delay, that suggests a session timeout issue. I would be fairly confident that the cookie contains session time information, for revalidation requirements if nothing else, however I've not looked, so happy to be proved wrong.
The developer was saying it was hard to reproduce, I was providing a hopefully useful suggestion as to how to reproduce the error. I have absolutely NO issues with login or session cookies so I'm not sure why you suggested I needed to clear my cookie cache
As a possible source of the error. Try typing a message then leaving the browser go make a cup of coffee, read your emails, etc etc. Come back in 30 mins or longer and click submit reply.
This will probably trigger the error as its my guess its a timeout, as it usually happens when I've written a long wall of text or something thats taken quite a while to research and craft.
As an aside can the behaviour of the text box when submitting an initial message be changed? At present when used on firefox (possibly others but I only use firefox) when you type a message instead of wrapping the text at the end of the line you get a horizontal scroll bar and the text just keeps on going with the bar getting ever longer. This seems odd behaviour when the edit message box works just fine. This is what leads me to editing every message as I dislike the horizontal scroll method.