I have several people trying to upload images along with other documents but error comes up!

One person sent me the form and it all seems to be complete & properly done but when she hits submit and error pops up! Files could not be uploaded. Please go back and fix the problem. I checked her file sizes and they seem to be as requested 

I cloned your form to test it and was unable to reproduce the issue.  I removed the payment field in order to test but that shouldn't have an impact on the uploads.  The clone completed submissions successfully and all files were included. 

Is your form embedded to a web page by any chance?  Let us know if the issue persists and we can look into this further.