Gen 8.6 DTU "Unhandled event loop exception" and code does not display

Products

• Gen

Issue/Introduction

On two different machines on entry to a particular Gen 8.6 model procedure step (PStep), the Diagram Trace Utility (DTU) either fails to load the action diagram code in the bottom panel or loads it with no colour.
On the same machines the DTU behaves correctly for the same PStep (slightly different code) in a different model.
Exiting the offending code the DTU session resumes normal behaviour for other code traced.

Some reported errors are:

Unhandled event loop exception

Error opening the editor





The DTU log file "%USERPROFILE%\AppData\Local\CA\Gen 8.6\cfg\DiagramTrace\workspace\.metadata\.log" shows similar errors:

*****
!ENTRY org.eclipse.ui 4 0 2026-06-24 15:55:55.247
!MESSAGE Unhandled event loop exception
!STACK 0
org.eclipse.swt.SWTException: Failed to execute runnable (java.lang.IllegalArgumentException: Argument not valid)
...
Caused by: java.lang.IllegalArgumentException: Argument not valid
 at org.eclipse.swt.SWT.error(SWT.java:3547)
 
...
 
!ENTRY org.eclipse.ui 4 0 2026-06-24 16:07:52.606
!MESSAGE Unhandled event loop exception
!STACK 0
java.lang.NullPointerException
 at org.eclipse.jface.text.PaintManager$PositionManager.managePosition(PaintManager.java:150)
 
 
...
!ENTRY org.eclipse.ui 4 0 2026-06-24 16:18:49.437
!MESSAGE Unhandled event loop exception
!STACK 0
org.eclipse.swt.SWTException: Failed to execute runnable (java.lang.IllegalArgumentException: Argument not valid)
...
Caused by: java.lang.IllegalArgumentException: Argument not valid
 at org.eclipse.swt.SWT.error(SWT.java:3547)
...

!ENTRY org.eclipse.ui 4 0 2026-06-29 12:50:58.693
!MESSAGE Unable to create editor ID com.ca.gen.diagramtrace.ui.editor: Argument not valid
!STACK 0
java.lang.IllegalArgumentException: Argument not valid
*****

Environment

Gen 8.6 Diagram Trace Utility (DTU)

Cause

Clearing the DTU cache was tried without success i.e. stop the DTU and rename the directory "%USERPROFILE%\AppData\Local\CA\Gen 8.6\cfg\DiagramTrace" to force creation of a new DiagramTrace directory.

It was later found that the DTU did not report errors after disabling the following single complex SET statement containing multiple and nested functions:

    3 |  SET local4 workset1 generic_text_254 TO
    3 |              concat(concat(concat("explorer", substr(local1 entity1
    3 |              long_description, 1, local2 ief_supplied count - 1)),
    3 |              substr(textnum(local3 entity2 numeric1), 4, 12)),
    3 |              substr(local1 entity1 long_description,
    3 |              local2 ief_supplied count + 4,
    3 |              length(trim(local1 entity1 long_description)) -
    3 |              local2 ief_supplied count - 3)) 

Resolution

As a workaround the user split up the single complex SET statement into multiple simpler SET statements to enable successful use of the DTU.

Additional Information

Support did try to recreate the DTU errors after creating a simple model with a similar action diagram SET statement.

1. They tested both under the latest Gen 8.6.4 Consolidation PTF  WKS86400 and with the user's earlier PTF level but could not recreate any errors.
   
   
2. Duplicating  the SET statement several times in the action diagram to see if more code would trigger an error also was not successful.
   
   
3. It maybe that either the data involved could be a factor in causing the errors or perhaps it needs the rest of the code in the problem PStep is required as well as the SET statement to cause the errors.
   It was not possible for the user to send a subset with the problem PStep for further testing by Support.