When running the winforms its showing error

ContextSwitchDeadlock typically happens when a thread in your application is blocking the UI thread, causing it to be unresponsive and unable to process Windows messages.

You need to check the below points:
1. Any long operations or tasks should be run on a background thread to prevent blocking the UI. For that you can use BackgroundWorker or Task or async/await method.
2. Check that your code does not have deadlocks, where two or more threads are waiting for each other to complete.