VMWare Fusion 5: Could Not Open /dev/vmmon: No Such File or Directory.

I ran into this issue recently with VMWare Fusion 5. All of the sudden none of my virtual machines would start. They would all error out with “Could not open /dev/vmmon: No such file or directory.”

After much head banging I remembered that I had recently installed Intel HAXM. Taking a stab in the dark I uninstalled HAXM:

sudo /System/Library/Extensions/intelhaxm.kext/Contents/Resources/uninstall.sh

Voila! All of my VM’s happily start. My emulators run extremely slow, but at least I can run virtual machines. Will update if I figure out how to get them running in parallel.