Odd bug where vms either don't close correctly or it incorrectly finds ones running.

[daemontroll]

I think I stumbled onto a bug but not sure. Recently when I have gone to launch a vm from Virtual Buddy it will error when I try to hit run. It will give the error that there are too many virtual machines running. At the time I am usually just launching Virtual Buddy and this is the only one open.

When that happens if I close the vm that would not start and try to quit Virtual Buddy it will present the message that vms are running. Even though this is the first one I have started and it failed to run. It give the option to quit or shutdown the vm. If I quit it just quits, if I choose shutdown it just hangs and I have to force quit Virtual Buddy.

Once this happens the only way I have found to clear this message is reboot the Mac. Once rebooted the vm runs fine.

Some days it will run for multiple days with out issue, other times every morning I get this error.

I am not sure what or where to look to identify further the cause. Normally I am just running the one vm in Virtual Buddy. Every now and again I run a vm in VMWare Fusion but when I do it closes and shuts down successfully every time.

Any help or tips would be appreciated.

[insidegui]

This sounds like it could be a bug in macOS where the system believes VMs are still running when they aren’t actually running, but it could also be that there are VMs running but you’re not aware of them, such as VMs used for Docker (or Apple’s new Containerization system).

That is then being made worse by what seems like a bug in VirtualBuddy where it’s flagging a VM as running even when it has failed to start, so when it attempts to terminate the VM, it just waits forever because it was not actually running.

If you’re able to reproduce this again, I suggest looking in Activity Monitor for com.apple.Virtualization.VirtualMachine or similarly-named processes. If there are processes for VMs active even after you quit VirtualBuddy, then those are not virtual machines that were started by the app, as the system will automatically kill VM processes once the app that requested them is no longer running.

[daemontroll]

Thanks for the suggestion. When that occurs again I will check that. I am not running any containers either in docker or Apples containerization. I have not gotten that error in vmware or seen anything indicating an errant running vm or container. I think it is incorrectly seeing one as running where it isn't but not sure how to check that. But on the next occurance I will check activity monitor for any signs of container or vm then see what I find.

[daemontroll]

Ok, I figured out how it happens. I have a macOS vm that runs in virtual buddy that I normally use daily. I also have three others that I use occasionally for testing. I had the first one running, started one of the other vms, ran a few things, and then shut it down. I then tried to start another vm in virtual buddy and I got the error.

I had not run any other virtualization software. I still have the first one up but after shutting down the second one I can not any other vms. Even the one that I had just shutdown will not start up. When I try to start any vm as the second one right now I get the error below:

The machine has stopped due to an error: Error Domain=VZErrorDomain Code=6 "The maximum supported number of active virtual machines has been reached" UserInto= NSLocalizedFailure= The number of virtual machines exceeds the limit. NSLocalized Failure Reason the maximum supported number of active virtua machines has been reached.

In console I get the message below:

1 duplicate report for Sandbox: ContextStoreAgent(869) allow file-read-data /Applications/VirtualBuddy.app/Contents/MacOS/VirtualBuddy

When I check activity monitor for com.apple.virtualization.virtualmachine I get nothing.

When I check for virtualbuddy I get two entries, virtualbuddy and virtual machine service for virtualbuddy.

When I check for virtual machine I get just the one virtual machine service for virtualbuddy.

When I check for virtual I get a bunch of com.apple.gpusw.paravirtualizedgraphicsgputask, and a platformidentity.

With the second vm open but not started or running activity manager appears the same.

So now I have figured out how to trigger it. It is definitely an issue either with the OS or Virtual Buddy. I have not tried to do a test in another virtualization software to see if this same issue exists. But the root is running one vm in virtual buddy, starting another one, shutting it down and trying to start another vm.

[daemontroll]

Update when I shutdown all virtual buddy vm's and went to quit virtual buddy it gave me the error that one was still running. I chose quit. I then tried another virtualization software and although none are running it reported that the number running has exceeded the allowed number. When I look at activity monitor for virtualbuddy it shows nothing running. With all vms and virtual software shutdown if I look for virtual I get two entries com.apple.virtualization.eventap and applevirtualplatformsystemservice.

If I quit either one they respawn. After quitting both I try to launch a vm and it still reports too many vm's are running.

I looked through the other processes and do not see one that seems like it would be linked to this. Not sure if those two processes listed above should be running when no vm's are running or not. But I will check on that one later.

[insidegui]

That's really odd.

I should've asked before, but can you let me know:

1 - The host Mac model
2 - The host macOS version
3 - The macOS version of the guests involved
5 - The version/build of VirtualBuddy
6 - How you're shutting down the VMs (Apple Menu > Shut Down, or some other way?)

[daemontroll]

Yeah it is really odd. I think it started when I updated to macOS 26 Tahoe but not certain as the times I run multiple virtualbuddy vm's are not too frequent.

But for the questions you asked, yeah sorry about not including those details.

1. MacBook Pro 16 M3 Max
2. At the time it started I think the host was macOS 26 Tahoe. When I reported the issue it was macOS 26.0.1 and I updated to macOS 26.1 but it seems to still have the same issue.
3. At the time that I noticed I think the guests were mostly macOS 26. I had one test vm running macOS 15 Sequoia but I rarely run that one. Most of the time it is a couple of guests running 26. But when I posted this they had also been updated to 26.0.1 and are now running macOS 26.1 but still have the same issue.
4. The VirtualBuddy version is 2.1 (325). That has not changed recently to my knowledge but I could be off on that part.
5. I am shutting down all of the guests the same way. Apple menu > Shutdown, then once powered down close the window.

I hope that helps but let me know if you need anything further.

[grahampugh]

Hi, I just want to add that I have frequently seen this for the past year or so. Eventually fails to launch a VM - when I press the Play button, it just stays on the thumbnail/start image. Typically, this will be a VM I left running for a long time in the background/forgot about. So I close that window, close VBuddy, and then launch the VM. But, I'm pretty sure that one I closed is still there in the background in a stuck state. This time, when I shut down the open VM and then try to close VBuddy, I get the same error reported above that there's still a VM running. It's after this that I'm most likely to see the "The maximum supported number of active virtual machines has been reached" error.

I've seen this on multiple Macs, on Sequoia and Tahoe.