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Absolutely the same issue here, been trying to remove or edit the message, in the end it was basically just a "I am looking for an assistant to help handling some documents in Dubai" and guess what? Still the same error message. I tried Safari and Chrome, all the same result.
This is not just a waste of time, if I need to spend so much time and efforts researching for solutions on how to post a simple message, I could've just use this time to find a freelancer on those Facebook groups or even by asking for referals from colleagues and friends.
If upwork doesn't fix this soon, this is still a place where a lot of startups and creative people gather, I wound't be surprised new alternative platforms would spring up and just provide something more stable, I would probably even use "got a code snippet problem? go to blah blah blah.com" as a tag line.