What Wes said, but...
Did you keep attempting to connect after getting that message? If so, what happened?
I see the sequence below Every Single Time I connect, and it's been reported by others from time to time, as well. The stumbles are annoying, but they're basically click-through and I'm in.
Attempt #1: Error Connecting msg
Attempt #2: No message, but no success, either
Attempt #3: Connection sucessful
My guess (and that's all it is), from some connect-disconnect-connect cycles that I've run, is that the first bump or two probably has more to do with the FTDI driver becoming active and making COM ports available, than with ASCOM or the PMC8 driver.
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT
Cameras: Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer: Thinkpad x230, Win7Pro/64