Hi, I was wondering whether participants get a warning if they submit a wrong completion code? I had a bit of a ‘situation’ last week where a participant clearly had not read study instructions and wanted to use a token given in the study as the completion code. I would have thought that a four-digit numerical code can’t even be submitted or that they get a warning but may be mistaken. Thank you for your help!
Hey Sandy, welcome to the community! 
Participants don’t get a warning when they submit an incorrect completion code, because sometimes they don’t receive the code in error, so we give them flexibility to enter a code manually.
If a participant completes the study without entering the correct code, should be highlighted in your Submissions page.
For more info on how to deal with incorrect code submissions check out this article.