VB failed to open a session

[Muyfa666]

Hi there.

I just installed lastest VB to run Win 10 Preview.

VB crashes with the message "failed to open a session".

I am running the latest Sierra beta.

Any ideas on what could be the cause of this?

[socratis]

There are a lot of things that could be going wrong for a message like this. First of all, we need the exact conditions that triggered it (did you try to run the VM?) and the exact message. Even a screenshot would do, if you have to. The unfortunate thing with screenshots is that they're not searchable, that's why it is a last resort.

But you might have a problem with Sierra beta. I don't know. Betas are not usually supported.

[Muyfa666]

I can not even get the VM to start. It crashes instantly.

[socratis]

It's funny how you only read the question in parentheses and you skipped all the rest...

Moving to "VirtualBox on Mac OS X pre-releases".

[Muyfa666]

The error message is exactly this;

"Failed to open a session for the virtual machine [Name of the VM]."

Then I got a huge error report that is too long to post... :-/

[socratis]

I got a huge error report that is too long to post...

Big or small, we need it. If it's a text file and it's too bit to post, compress it. And please do not obfuscate the information. It's sort of ... vital, otherwise it wouldn't be there. There is a huge difference between [Name of the VM] being "DOS" and another if it is "Latest test build of Windows 12 experimental".

[loukingjr]

FWIW, Windows 10 and other guests run just fine on MacOS Sierra. Other than the audio issue.

[Muyfa666]

The name of the VM is "Win 10 Preview". I am trying to get Windows 10 Insider Preview Build 14393 running.

[loukingjr]

(pic removed)
I should have been more specific…

[Muyfa666]

How do you mean? I can't even get the VM to run, no less install a OS on it.

[loukingjr]

A VM can't run until an OS is installed.

[socratis]

A VM can't run until an OS is installed.

Yes it can. It won't get you far, but it can run. From what I understood so far is that 'Muyfa666' can't even get to the point where the virtual BIOS takes over. It crashes at inception.

@Muyfa666
Do you get a VBox.log created at the path "<Your_VM>/Logs/" directory? If you do, that's the one I had in mind, I should have been explicit about it. If not, can you please post the output of the command:

• kextstat | grep -v com.apple

Also, the exact version of your OS and VirtualBox version. Finally, please state anything "unusual" done to your OS. From antivirus to MacPorts, to custom Python versions, to... anything. Although as I said again, it's a beta, and as such differences and minute annoyances (like a crash) are in the norm.

[loukingjr]

A VM can't run until an OS is installed.

Yes it can. It won't get you far, but it can run. From what I understood so far is that 'Muyfa666' can't even get to the point where the virtual BIOS takes over. It crashes at inception.

I guess I never tried.
My guess is a third-party app he has installed is causing a problem. Not many would be updated for MacOS. Or could be a bad VB install
All my guests run normally in MacOS Sierra 10.12 Beta (16A270f).

well except for the lack of audio introduced in VB 5.1. I may have mentioned that already.

[socratis]

except for the lack of audio

I hear you. Loud and clear

[loukingjr]

I'm too stubborn to roll back.