Web Client Exception error on HTML

We are on ERP 8.0. Accessing Apps on HTML seemed to be working fine a few weeks back. We just did a successful full package build last week.Then we regenerated the Serialized Objects on the Web Server. All apps seemed to be working fine except P4210 - on this app we now keep getting this: Web Exception Error. An exception has been caught by the Web client. Please contact your system administrator. See log for details.

I saw something on the KG about entries in the GenApp.ini file for Mode 3. We have 2 entries for the P4210 in our GenApp.ini the first one is set for Mode 3 (HTML), the second one for Mode 2 (JAVA). All the other entries for other apps seem to be in the opposite order (first Mode 2, then Mode 3). Not sure if this is a clue or related to the issue at all... to my knowledge, the GenApp.ini has not changed lately.
In addition, we have modified P4210 in the last pkg build, however, the app seems to be working fine on fat clients.
Does anyone have any clues?

Why don't you try generating P4210 by itself and see if you still get the error.

We've had the same issue with the P4210. On all occasions the Web Exception error was caused by our custom code. On one occasion an "Open Handle" statement had been disabled but not the "Close Handle" statement. On another occasion the mapping on a custom Table I/O had somehow been corrupted. The fat client worked fine despite these errors.

To test I suggest you disable your custom code and regenerate the app - it should work fine on the web. Once you're convinced it's the custom code that's causing the problem, you'll have to troubleshoot to detect the offending code.

In order to isolate the rogue code we used "dummy" statements (I use GetUDC with different values) around our code in order to determine at which point it falls over. Then it's just an exercise of trolling thru the debug log. This whole exercise is a pain, but I do not know any better way of doing it.

FYI: The KG has a link to a tool that allows you to dynamically switch the logging on/off on the Web.

Good luck!

Nazza