Braden this might be related to your issue discussed earlier in https://discuss.flarum.org/d/26314-something-went-wrong-while-send-topic-message
I've seen regularly some people having that issue, but it's so rare and without any precise way to reproduce it's difficult to say what's wrong.
My hypothesis is that it's always related to an earlier error that prevented an update of the post number counter. The previous error could be a failure to send mail, an extension making a call to an external API that fails, etc.
If there's no other error in your logs, does it happen reliably? Do you know a way to reproduce starting with a new discussion?
