Symptoms

File Attachment Control Intermittently Causing SmartForms w3wp.exe process to fault in call to StoreFileToRemoteServer
 

Diagnoses

We are in the process of upgrading the Microsoft MSCOM project from K2 4.6.11 to 4.7 and during QA we have discovered that Intermittently the File Attachment Control caused the SmartForms App Pool to crash. This happens when the user selects a file and clicks Ok in the file browse box, so it is happening outside of any rules on the form / view as there is no onChange event on the file attachment control.

During debugging we see the following Exceptions as we drill down. I have screenshots of all errors and the call stack in the attached word document.

1. An unhandled Microsoft .NET Framework exception occurred in w3wp.exe e83836]
2. APICommunicationException was unhandled --> An unhandled exception of type 'SourceCode.Hosting.Exceptions.APICommunicationException' occurred in SourceCode.Forms.dll. Additional Information: Not Connected

In the debugged while i don't have SourceCode.Forms.pdb I was able to get the method that the error originated from:

SourceCode.Forms.dll!SourceCode.Forms.AppFramework.FileUtility.StoreFileToRemoteServer(SourceCode.Forms.Management.FileInfo file, System.IO.Stream stream, int fileLength)

This issue does does not reproduce every time and doesn't seem to reproduce in rapid fire testing. The few times I have seen it on dev it seems to happen after I have walked away for a time with the form up waiting for me to select a file (we spent most of the afternoon yesterday trying to determine how to consistently trigger the issue) so while I am not sure there seems to be a time component to the repro. The good news is I have reproduced it in a K2 Core 6.1 VM (in addition to the clients test enviroment) and have a Hyper-V checkpoint with it in a state where it Repros (I've applied and tested 4 times and so far a 100% repro rate on the checkpoint).

 

Resolution

Fix was rolled into fp3.