Error response from daemon: open \\.\pipe\docker_engine_linux: The system cannot find the file specified
In my case, the reason for the error was even easier than the main answer ("close and open it again") suggests. Docker Desktop was just not running anymore!
When I hovered over the tray icon, it vanished.
Further details:
Docker Desktop had crashed, or it was closed because of a forced update. I had this problem after updating Java runtime environment.
When I opened Docker Desktop then, an update ran, and I could not even choose between yes or no, running for at least 5 minutes with the tray icon only showing "Docker Desktop is starting". The menu had crashed as well.