Disclaimer: I’m still new to Discourse. I’m using it to teach online classes at the university where I teach.
I had a student complain that he couldn’t post and he’d tried all kinds of things (different computers, different browsers, different locations) but still couldn’t post. The error message he was getting when trying to post his work was
"Something has gone wrong. Perhaps this topic was closed or deleted while you were looking at it?"
which is the topic_not_found error. I poked around a bit more and finally realized that his account was blocked. It would be nice if the error message reflected that so that he or I could have figured out the problem a bit quicker.
I don’t know why he was blocked. Perhaps too many accounts got created from the university (which is behind NAT, so it looks like one IP address)? On a related note (which might need another topic?) it might be nice if there were a way to whitelist an IP range and/or a email domain. I also went crazy when I had a bunch of students log in during the first class and was flummoxed that they couldn’t reply because they were still Level 0 users. (In the future, I can change the initial user level for the first week or so of class, or make them read the syllabus in Discourse before I have them try to post.)