Sigh, this an age old problem with USB serial port emulators. Serial ports are devices that date from the stone age. They used to be screwed into the bus, no way to remove them while a program is using it without drawing sparks and billowing smoke. Stone age also includes the lack for any kind of plug-and-play support so that a program could detect that the device is suddenly gonzo.
Unfortunately, the majority of the crummy device drivers that emulate them just make them disappear, even though a program has the port opened. This works just about as well as jerking a flash drive out of the socket when Windows is writing files to it. There's a background worker thread that waits for notifications from the device driver so that it can generate the DataReceived, ErrorReceived and PinChanged events. That thread suffers a heart attack when the device suddenly disappears. You can't catch that, it is a thread that was started by the SerialPort class, you can't wrap it with try/catch.
By popular demand, Microsoft did something about it in .NET 4.0. Not actually sure what happens in that release. If you're stuck on an earlier release, the only reasonable thing you can do is tape a sign next to the USB slot: "Don't remove while in use!" Which inevitably makes somebody unplug the device at least twice to see what happens. After which they get bored with that and leave you in peace.
The very unreasonable workaround is an app.exe.config file with this content:
<?xml version ="1.0"?>
<configuration>
<runtime>
<legacyUnhandledExceptionPolicy enabled="1"/>
</runtime>
</configuration>
Don't use it.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…