"FlashControl.Enabled = true" throws FileLoadException occaionally

Hong 1,051

FlashControl flashControl  = myMediaCapture.VideoDeviceController.FlashControl;
flashControl.Enabled = true

The above code usually works fine, but "flashControl.Enabled = true" occasionally throws the following:

System.IO.FileLoadException: The process cannot access the file because it is being used by another process. (Exception from HRESULT: 0x80070020)
Stack Trace:
at System.Runtime.InteropServices.McgMarshal.ThrowOnExternalCallFailed(Int32, RuntimeTypeHandle) + 0x21
at __Interop.ComCallHelpers.Call(__ComObject, RuntimeTypeHandle, Int32, SByte) + 0xc0
at __Interop.ForwardComStubs.Stub_24TThis + 0x37

Could anyone shed some light on the possible causes?

AryaDing-MSFT 2,841 Reputation points

2021-05-31T06:54:34.36+00:00
@Hong As this part of official document mentioned, if FlashControl.Supported is false, attempting to access Enabled property will throw an exception. Therefore, maybe you need to check the value of the FlashControl object's Supported property before attempting to access this property.

For example:

if (mediaCapture.VideoDeviceController.FlashControl.Supported) { mediaCapture.VideoDeviceController.FlashControl.Enabled = true; }
Hong 1,051 Reputation points

2021-05-31T12:10:20.413+00:00

@AryaDing-MSFT Thank you for the tip. I am sorry that I omitted some code for brevity. The app checks VideoDeviceController.FlashControl.Supported as follows:
if (mediaCapture== null || !mediaCapture.VideoDeviceController.FlashControl.Supported)
{
// do nothing
}
else
{
//set the flash
...

}
AryaDing-MSFT 2,841 Reputation points

2021-06-01T07:00:36.003+00:00

@Hong It is hard to locate this issue if you could not reproduce this issue. If you are able to collect the dump or log file of this issue. I'd suggest you open a support ticket for this. Please contact our paid phone support at MS Support. You will get 1:1 support on that. Please kindly note that your support ticket will be free if it is Microsoft's issue.