Show an unsupportedFormatException

Have a program in 2015r2.1 where I open a window called Customer. This is a toolbar option so is a Menu Handler. The code is


This has worked for days and the window Customer appeared without any problem or delay. Today I received a UnsupportedFormatException
No code was changed that I am aware of so cannot understand why I’m getting the error. Help in understanding this would be appreciated.


There should be a stack trace or something IF you catch the exception in the app event for this - UnhandledException

Thanks. Will work on this.

If the window has any ListBox controls, check each ListBox.ColumnWidths property for an illegal expression (including invisible characters.) The ColumnWidths is evaluated when the window opens and will raise an UnsupportedFormatException if the expression is invalid.