Why this message appeared suddenly?

Hello,
I was working on a task and at the moment I clicked on submit this message appeared: " There was an error submitting your assignment.
Sorry, your work cannot be accepted because it violates our guidelines. If you believe this is an error, please contact our support team using the Help link above."
I'm sure I have respected all guidelines. Any explanation please?
Thank you

Don't worry, sometimes it happens. It's a problem with the crowdflower task, not your fault. If you click the "back" arrow on your browser the same task will reappear and you can put all the answers again and then re-submit. Most of the times it works like that. If not, you can give up on that task and re-open the same task to get a new one that probably doesn't have a problem. ;)