Web client exception error

We are on E1 9.0, tools 8.98.42.

While entering a voucher in AP, the user presses ok and receives a Web Client Exception error. A screen shot is attached. Looking at the agent log and root log, there really isn't more info that on the error pop up.

The text of the message in the root log is as follows.

'An exception has been caught by the Web client. Please contact your system administrator. See log for details. Exception id =Exception_2014-04-11 13:00:30.920_NELLUMSM There was a problem with the sever while running the business function F0911FSEndDoc.\nPlease exit the application and restart it.\nPost Button Clicked Line number 3\nP0411_W0411K com.jdedwards.runtime.base.SystemException: There was a problem with the sever while running the business function F0911FSEndDoc.\nPlease exit the application and restart it.\nPost Button Clicked Line number 3\nP0411_W0411K'

Any thought on what I might be dealing with here? The user reentered the voucher with no issue and as far as I can tell this is the first time this has occurred.

You'll want to check the enterprise server where the business function was running. The logs for the call object kernels will should have more information. Doing this postmortem can take time as you may need to hunt through a bunch of log files.