Xojo Exception Error in Windows

Hey all,

I’ve seen a couple instances where customers are getting exception errors with the following stack trace:


I’m not sure what it is because these are all Xojo methods, not any of mine. I am not sure where the error is happening or why. I know it happens on startup. I’ve seen customers with it on Win 7 and Win 10 now. But I’ve not been able to make it happen.


Seems like it’s all related to Xojo 2018r4.



My customer had this one in his log today. With application build with 2018R4 and running on win10. Never had this myself and I have no idea why this happened. According to the log it happened in a timer-action event with nothing special in it.

Was his the same exception I list above? I’m wishing I’d stayed with 2017r3.

My application logs all exceptions and messages with as much details as possible. I will keep an eye on the logs.
Up till now I am quite happy with 2018R4 on windows, lot’s of issues are solved compared to 2017R3.

BTW, my builds are 64 bits on Win10.

I’ve discovered the problem that causes this.

If for any reason a control has a height <=0 then this happens on Windows. I have a placard and container control that have some calculated sizes based on the size of the parent window. When the program is first installed, I have no configuration data saved for the program operation and the controls that are in that container control don’t exist yet. So I shrink the main window to a smaller height. This causes the calculated height of the placard and container control to be less than 0. The old Windows graphic framework (prior to 2018) didn’t seem to mind this. The new one throws this runtime error.

If I set the heights of the placard and container control to anything > 0, then it’s all fine. But instead what I’ve decided to do is simply close them. I rebuild the window after getting configuration data loaded so it doesn’t matter if they are closed initially.

I have a Feedback case opened as I think Xojo should handle this more gracefully.


Yes agree, but not a big deal for experienced users as we are. Happy to read it’s not going to be a big and uncertain issue.

You should have some hardcoded initial settings to start with in case there is no configuration loaded.