Good Morning, We have couple of documents attached to the Form from Email

Does the user that is seeing the error have access to the folder it's being saved into? Check the folder security to see if that user has access to write to it.

One quick suggestion is try the same file after renaming to a shorter file name .. Also you said other files are not having an issue .. So are those files are of same extension ? Narrow down the issue by comparing the files and its properties ..

Did you check the file size? I think there are some configurable limitations on the webserver or JBoss.

look at your app server logs. There should be some good info there.

@ramaseshur As said by Michael, drilling down through logs for 'Caused By' at the time of uploading the file would be a good starting point and perhaps it might give you leads as well.

Thank you all for the prompt reply,
Lakshmi, yes they all have access to those folder.
kumar, we do have files with longer names all the time, Actually we append time stamp to these files at the later stage. I followed your advice and its interesting to see that conflicting files are PDF's and non conflicting when i upload a DOC file. When i tried to replicate this issue it's not happening anymore!

stefanh 791, Checked and made sure that size is not issue, I tried uploading a video file of 70 Mb as an file and still not able to replicate this error.

Micheal and Sikhivahans,
I tried to look into the error logs and found this error with
13:51:30,059 INFO [stdout] (ajp-/0.0.0.0:8009-13) 2015-11-23 13:51:30,058 [ajp-/0.0.0.0:8009-13] ERROR com.appiancorp.rest.shared.AppianExceptionMapper - Internal Server Error on REST API invocation.
13:51:30,059 INFO [stdout] (ajp-/0.0.0.0:8009-13) com.appiancorp.suiteapi.common.exceptions.AppianException: Could not upload “scan077419_20151123_120029860_0”. Reason: An unexpected error has occurred. The form can’t be submitted