Issue on mac OS Big Sur? I get a message "The File can't be found" when I plug in my iPhone X via USB

Welcome Redge777,

Thanks for joining Apple Support Communities, happy to have you with us! Based on your post, when you connect your iPhone X to your Mac, it continues to pop up windows that state, "The file can't be found." We'll do our best to assist.

To begin, we'd isolate this further by testing it in another user. If you need to create a test user, try these steps to create an Administrator user account: Set up users, guests and groups on Mac Then connect your iPhone to the Mac to see if the issue occurs there.

If it continues in the other user, navigate to Settings > General > Reset > Reset Location & Privacy on your iPhone to reset the trust with this computer.

Should it not continue in the other user, open the Image Capture app, from the Applications folder. Then change 'Connecting this [device] opens' to 'Image Capture' as shown here: If Image Capture doesn’t open when you connect a device to your Mac If that solves it, you can set it back to 'No Application' or 'Photos', etc.

Still having the issue after these steps, then we'd recommend to Contact Apple Support

Take care.