There currently seems to be a bug with the automatic message popping up whenever a question is asked/edited with an ID-tag (identify-this-movie, identify-this-tv-show, ...). The reminder message, that should just kindly remind you to include any possible meta-information seems to suddenly be treated as a hard error, making it impossible to ask or edit the question as long as it has this tag.
Seeing that this feature worked well for a long time and this bug is only ocurring rather recently (first encountered with this question), there seems to be something off. This should be investigated as fast as possible, since it basically prevents people from asking any kind of ID question (as much as I personally like this situation ;-)), or even worse, makes them ask those questions without proper tagging or possibility for retagging. If this is not solvable that easily/fast, the automatic message should simply be disabled for now (unfortunately this seems to be a feature not even accessible to moderators but only to SE staff).