Worker doesn't launch on Windows 11 system

I have a client running my Mac/Win desktop app on Windows 11. He has two systems where my app from the front end looks like it hangs for a feature that uses a worker. This app was released over a year ago and I haven’t had anyone else report this error, which is a core feature.

Over the last week I’ve sent him special builds of my app which creates a log file to the desktop. The worker is launched (.start called) from a thread. The worker has .CorePercent = 90 and .MaxCoreCount = 128. Execution of the thread is logged before and after worker.start. However, the same log file contains absolutely nothing from the worker itself, including the start of the JobRequested event handler. I’ve tested the same app on my Windows 11 system and all works fine.

Does anyone have an idea what may be stopping my app from launching its worker on these client systems on Windows 11? The client is very helpful so I can build a small test app for him to run. Apart from creating log file calls around the worker start and from within the worker as I’ve done with my production app, is there anything else I can check for? In case there’s a write permission issue from the worker, is there a better way to log from a worker that doesn’t require a lot of work for my client? Are there any security apps or Windows settings that can stop a worker from launching?

App built with Xojo 2025r3.

Many thanks, Mark

Apps launching other apps is sometimes the sign of a virus. Did the customer get a warning te first time and click “block”?

Hi

I have the same problem with apps built with xojo 2021 to 2025r1. The app hang when tying to start the worker. In my case the problem was solved moving to xojo 2025r2.1. I have not tried building with later versions.

/HN

My client replied last night to say they never clicked a block message, but when they add the worker exe filename to the Windows Defender exclusions list, my app is able to launch the worker.

Virus & threat protection > Virus & threat protection settings > Manage Settings > Exclusions > Add or remove exclusions

Thanks @Greg_O for the reply.

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alternate to Worker are preemptive Threads, they are a bit slower but in the same app.

see “Safely sharing resources between Threads”
https://documentation.xojo.com/api/language/threading/thread.html