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BobbyBoogie
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"Could not open /dev/vmmon: No such file or directory." Error

I recently cloned my Mac from a 2011 pro to a 2015 pro. I've also updated to High Sierra. My VMWare Fusion is now displaying this error:

"Could not open /dev/vmmon: No such file or directory.

Please make sure that the kernel module `vmmon' is loaded.

Failed to initialize monitor device."

I've reinstalled Fusion 8.5 and have rebooted several times. I still get this error on my existing virtual machine file, along with any new ones I try to create and open.

What can I do?

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GertJanA
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Looking through the community, I found another topic about it: High Sierra "vmmon"

I had the same issue, but managed to sort it in a quicker way.

Open VMWare Fusion and start an image.

You will probable get the error of loading the vmmon kernel module.

Close VMWare Fusion.

Go To 'System Preferences' >> 'Security & Privacy' >> Check if you are allowed to run apps from identified developers and there is no mentioning of a block application.

In my case, VMWare Fusion was blocked, and after allowing it, the problem with the kernel module was resolved.

Hope this also fixes your problem.

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15 Replies
GertJanA
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Looking through the community, I found another topic about it: High Sierra "vmmon"

I had the same issue, but managed to sort it in a quicker way.

Open VMWare Fusion and start an image.

You will probable get the error of loading the vmmon kernel module.

Close VMWare Fusion.

Go To 'System Preferences' >> 'Security & Privacy' >> Check if you are allowed to run apps from identified developers and there is no mentioning of a block application.

In my case, VMWare Fusion was blocked, and after allowing it, the problem with the kernel module was resolved.

Hope this also fixes your problem.

___________________________________________________________________________

Did you find this helpful? Let us know by completing this survey (takes 1 minute!)

Choorel
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Thank you so much for your answer.  It was an easy fix, but it had eluded me.

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Table23
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uR write. It' b workin' 4 me. ThankQ@GertJanA !

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RayTrask
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To VMWare staff.  This happened as of Feb 10, 2018 when I migrated from a 2016 MPB to a 2015 MBP.

[Yes I went back in time, as I can't stand the 2016 keyboard and even worse. I was at a customer site and a kink in the power cord combined with no light on the USB-C charging port cause a big problem which was the last straw.]

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IconnectChile
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Works for me, Thanks so much.

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Arjani
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@GertJanA Thank you so much!

I had to reinstall VMware Fusion 8 because of a failure in my SSD.

These few steps arranged the opening to my Windows 7 and 10 again. I have them stored on a external drive and this works perfectly.

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aalblake
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Yes it did, thanks.

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DJLambert
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Argh! why doesn't Fusion warn/prompt like other applications? I thought the 11.0.1 update borked something up so wasted time manually uninstalling. Bah.

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zeighty
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Worked for me... Thanks... This kind of problem is the perfect example of you should be searching before guessing.

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pranav_karakava
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Hello,
I have the same problem but it is with VMware Workstation player on Linux Mint.
Any help would be appreciated Smiley Happy
Thank you.

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tasmity
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Thanks!!!

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maxtamtam71
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Well spotted. That makes me more and more convinced that MAC OSX is getting more and more unusable for VMware usage and any professional usage in general except playing music and doing pictures.

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danlallouz
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So, i've recently advanced on a much-anticipated project: upgrading my Mac Pro 5,1, which was still running macOS 10.12 Sierra w VMware Fusion 8.5. I installed a metal-capable graphics card, allowing me to upgrade to Mojave, but really, to enable the usage of PCI-connected SSD m.2 drives (FYI the firmware to both use and boot from them is only installed when installing Mojave). 

I initially cloned my 10.12 Sierra drive to a new partition on the blade SSD, and upgraded to macOS 10.13 High Sierra, and used this install for a few days. So far, no problems w Fusion 8.5

I then cloned 10.13 HiSi to another partition on the blade, and upgraded that to macOS 10.14 Mojave. Upon opening two essential macOS VMs, I constantly got the "Could not open /dev/vmmon: No such file or directory" error, as well as for other VMs. I tried the Security pref pane solution above, as well as reinstalling Fusion 8.5, all to no avail. (Rebooting in High Sierra, the VMs opened fine.) 

I then installed Fusion 11.5, and received the same error!! Checked security prefpane, updated to 11.5.7, same thing. Grrr.

Then I realized something important: I had not shut down my VMs before the OS upgrade, and it was initially trying to restore their state. I also did a test mini-upgrade from HiSi to Mojave, keeping VMF 8.5, and this worked with no issues. I tested copies of the problematic VMs, keeping them on hardware v10, upgrading some to v12... all good 🙂 

So I started from scratch, and this recipe worked well: 

  • Deleted my Mojave test install
  • in High Sierra, shut down the VMs properly
  • made sure VMware Fusion was in the "accessibility" section of security PrefPane
  • ran a "deep clean" w Onyx (flush caches, etc etc – be careful with this!!) on my High Sierra boot drive
  • cloned HiSi install to new partition, tested
  • upgraded to Mojave, tested
  • ran Mojave security updates, etc, tested

Just finished this last step, and everything seems to be running well: the VMs are running, although I havent tested them thoroughly. I'll see how far I can push running Fusion 8.5, or may upgrade to 11 soon 🙂 

Have fun!

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ColoradoMarmot
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Couple of thoughts - do get to 11.5 as soon as you can (or at least have a good backup strategy).

FWIW, Onyx is actually one of the culprits that we think may cause this error - disk cleanup/permission changing tools like it, CCCleaner, etc seem to break something that Fusion relies on.

Once I got up into the Catalina/Big Sur and later OS's, I generally stopped running those utilities.  I do use OSX Cache Cleaner, but only to trigger the daily/weekly/monthly maintenance scripts and delete archived log files.  I don't even repair permissions anymore (not since Apple removed it from disk utility - took that as a hint that things changed underneath).

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Technogeezer
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You might also want to check this out:

The "could not open /dev/vmmon" issue can also occur when there are improper permissions on the /private/var/db/KernelExtensionManagement folder - this is not a Fusion issue as something has changed things under the hood in macOS that anything trying to load a kernel extension needs. 

See the reply in this thread from jameslodberg for information on how to identify if this is your issue and how to fix it without a complete re-install. https://communities.vmware.com/t5/VMware-Fusion-Discussions/VM-s-not-working-in-Fusion/m-p/2816692/h...

- Paul (Technogeezer)
Editor of the Unofficial Fusion Companion Guides
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