Collection was modified; enumeration operation may not execute. error on DataPortal.Execute

[kobi-shanti]

We have a WinForms application that is running CSLA v5.5.3. We've recently implemented an IIS application server, running a remote CSLA data portal using .NET Core 3.1.

Since our move to 3-tier, we have been experiencing intermittent errors whilst calling DataPortal.Execute for one of our CommandBase-derived commands. The error that is produced is "Collection was modified; enumeration operation may not execute.".

Through some testing and error trapping we believe the error is generated on the client side of the data portal, meaning it is not tied to the code in our command's [Execute] method. We think the error is occurring as a result of simultaneous calls to DataPortal.Execute being made from different threads in our application (main GUI thread and background thread associated with a timer) as this is the only time it appears to be occurring.

We've confirmed the error only occurs in 3-tier.

Does anyone have any ideas or potential solutions? Is this a known issue?

Let me know if I can provide further information to clarify our scenario.

Thanks!

[kobi-shanti]

We've found a few semi-related posts in the CSLA forum archives and we're starting to believe this error is due to CSLA not being threadsafe. Are we on the right track here?

[rockfordlhotka]

I was just getting here to say that the data portal wasn't threadsafe back then, because it is a bunch of static behavior.

In CSLA 8 the data portal is instanced, and is probably threadsafe.

[kobi-shanti]

Ok, thanks Rocky! We'll find a work around.