Error when inserting a new resume

Error when inserting a new resume

I am using the iframe code for inserting the resume form into my website (). However some of my users (ie those submitting their resumes for a job) are encountering errors when they do so. No record of their submission is found in the back office even if they get a successful message displayed.

Has anyone encountered this? Is it because I have added a field where they can upload their cv document?

Justyn