When "Submit for Approval", sometimes Message appeared. We cant understand why Unable to Submit with just message? So, need to output which condition Invalided, and customize error descriptions by criteria. Messages fixed ,so if over 20000 users meet this, to "contact" just one their Administrator, its crazy. Salesforce has some huge orgs, and should treat those as new stage just like this situation. We should work around this kind of issues with customizable messages.