Check if that another thread helps: Fusion 5 - Could not open /dev/vmmon: No such file or directory.---
Senior Infrastructure Specialist
It seems most of the replys in that thread center around " It seems that some driver on your system is triggering the problem by consuming all of the available "character device major numbers" (a small number used to identify a driver/device)." I am not sure how to identify which drivers are consuming the "character device major number" and even how to uninstall once they have been identified. One particular note is one person noted they had installed openVPN and removing it helped. How do I see if I have openVPN and how do I uninstall it?
Before you go and try to uninstall software, the first step in troubleshooting this particular issue is to reboot your mac.
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