.NET Windows Service needs to use STAThread

Question

I have created a Windows Service that will be calling out to some COM components, so I tagged [STAThread] to the Main function. However, when the timer fires, it reports MT

Answer 1

Setting the STAThread attribute will not work on a service. It's not being handled the same way as an application, so this will get ignored.

My recommendation would be to manually make a separate thread for your service, set its apartment state, and move everything into it. This way, you can set the thread to STA correctly.

However, there will be another issue here - you'll have to rework the way your service works. You can't just use a System.Threading.Timer instance for timing - it runs on a separate thread, which will not be STA. When its elapsed event fires, you'll be working on a different, non-STA thread.

Instead of doing your work in the timer event, you'll probably want to do your main work in the thread you create explicitly. You can have a reset event in that thread which blocks, and have your timer "set" it to allow your logic to run in the STA thread.