The error log used to give us the field name in this situation, so we could check which variable is being populated and then look at the variable to see what was submitted that does not match the field constraint. Now it just says this no longer indicating which field is the problem, so we have no idea which variable to look at.
Because this is the #1 mistake made on forms archives, and the archive wizard does not pre-check the conditions while the user is populating the template, when I go in to troubleshoot it is really important for me to know which variable to look at so I can quickly inform them on what needs to be fixed.