NilObjectException in WebMessageDialog WebMessageDialogButton

Seeing a crash in a Web 2 project in Xojo 2020r2.1 : feedback://showreport?report_id=63465

I think it’s happening when a session closes and a WebPage is being disposed of:

Session.UnhandledException 0 : RuntimeRaiseException
RaiseNilObjectException
Delegate.IM_Invoke%%o<WebMessageDialog>o<WebMessageDialogButton>
AddHandler.Stub.5%%o<WebMessageDialogButton>
WebMessageDialog._ExecuteEvent%b%o<WebMessageDialog>so<JSONItem>
WebSession._HandleEvent%%o<WebSession>so<_HTTPServer.HTTPRequestContext>
WebSession._HandleRequest%i8%o<WebSession>so<_HTTPServer.HTTPRequestContext>
WebApplication._HandleHTTPRequest%%o<WebApplication>o<_HTTPServer.HTTPRequestContext>
_HTTPServer.HTTPRequestThread.Event_Run%%o<_HTTPServer.HTTPRequestThread>
rbframework.dylib$6359
rbframework.dylib$6089
_pthread_body
_pthread_body

This seems very similar to a prior crash described in feedback://showreport?report_id=61476

Further testing shows this bug is a complete showstopper for me: sometimes the exception is raised in Session.UnhandledException, which means I can quit the Session (knocking that one user offline) but the WebApp keeps running.

However, sometimes the exception is being raised in App.UnhandledException. I tried ignoring these, but that causes some sort of infinite loop where the exception keeps getting raised over and over again.

The only solution seems to be killing the app at that point.

This is bad enough I’m going to have to revert to an older Xojo version, since I can’t use 2020R2.1 in production with these issues.

Xojo - Help!?

Huh - after posting this I checked Feedback.app and see that feedback://showreport?report_id=63465 is already marked as Fixed.

Aren’t we supposed to be receiving email notificatoins from Feedback? I received nothing.

1 Like

Last time I read something about this issue on the forum Xojo was handling things by email to work out specific bumps in the road. Try reaching out to hello@xojo.com to see if there’s anything they can resolve.

Submitted a similar (but perhaps different?) bug as feedback://showreport?report_id=63476 where I’m seeing this crash:

App.UnhandledException (none) 0 : RuntimeRaiseException
RaiseNilObjectException
Delegate.IM_Invoke%%o<WebMessageDialog>
WebControl._Close%%o<WebControl>
WebSession._RemoveAllControls%%o<WebSession>
WebSession._Cleanup%%o<WebSession>
WebSession._RaiseCloseEvent%%o<WebSession>b
_SessionShutdownThread.RemoveAction%%o<_SessionShutdownThread>
_HTTPDelegateTimer.Event_Action%%o<_HTTPDelegateTimer>
_Z13RunFireTimersv
rbframework.dylib$10052
_Z11ModalEventsh
RuntimeDoEvents
ConsoleApplication.DoEvents%%o<ConsoleApplication>i8
WebApplication.Event_Run%i8%o<WebApplication>A1s
_Z36CallConsoleApplicationRunEventHelperv
ConsoleApplication._CallFunctionWithExceptionHandling%%o<ConsoleApplication>p
_Z33CallFunctionWithExceptionHandlingPFvvE
RuntimeRun
REALbasic._RuntimeRun
_Main

Update: I was forced to all the way back to 2020R1.2 to avoid these crashing bugs, which make 2020 R2.0 and 2.1 unusuable for me.