CyberGene there must be more to this. If the discussion became invisible to your own user in the meantime, you would get a "not found" error. If the discussion was still visible but you could no longer post, you'd get "Unauthorized". And for most other errors you would get a validation error.
If there's something went wrong message, it's either server-side and will be logged to Flarum log file, or it was a temporary issue client-side or in transfer, like an internet connection drop of an error with a web proxy.
