[SOLVED!] Sorry for the false alarm. I didn't realize that Unity had switched the target platform to the Web Player (don't know why it did that). After setting it to Desktop, all works fine again. Hi, in earlier Unity versions, I successfully used the System.IO.Ports namespace in order to access the serial port. This seems no longer possible in the latest Beta, although I use the full .NET framework and not the subset. I get the following error: The type or namespace name `Ports' does not exist in the namespace `System.IO'. Are you missing an assembly reference? Is this intentional?