Used stamps exchanges.

I had just written https://100stamps.club/discussions/messages/351 and saved it, then revisited it via the list of questions https://100stamps.club/discussions/subjects/5. After a few minutes of inactivity my browser (latest Firefox under Win10) complained that the connection was gone, I did a refresh, the browser warned me that it had to resend information to which I said 'fine', and now my question is a dupe.

I understand that the resend caused this, but why was the page in some sort of 'edit' state when I just read my question back? It is not even possible to edit ones own question once they have been posted...

Additional note: this seems to be a common problem because I see more duplicate posts ;-)

OK, here is a reproducable method to cause the error:

1. I just added the "I just got a similar situation again" comment from 21:32, pressed the Add button. The green message "The message was added!" appeared and my new comment was visible as the second post in the thread
2. I clicked the Home link
3. I clicked Back in my browser

This again gave the 'Document expired' error. That should not happen, there was no pending edit at step 2.

I just got a similar situation again, here's more info.

It happened when I clicked the back button in my browser, but that previous page was *not* an edit page. In this case the URL said
https://100stamps.club/discussions/subjects/4#form