In This Scenario we will debug a VM is that is not Booting.(after it was working for a while).
In this scenario we are debugging the Guest OS and not the Platform.
First we need to understand if it's booting fully and not accessible or if it's failing and on what phase.
- Go to Azure Portal and Enabled Boot diagnostics. (This will expose the boot.log).
- You need first to set an storage account to save the log and to checkbox the Boot diagnostics.
- Reboot and refresh the Blade (do you see any errors on your boot.log ?).
- Did you change fstab add new mounts /Disks and forgot to verify mount -a ? if yes then you will need to mount this vhd OS disk to a running Linux and correct your fstab .
- Did you push a new Extension ? Check on the Portal once the VM is running the Extensions Status.
If this Process didn't help.
If this doesn't solve the Problem.
Feel free to raise a ticket for our Azure Support and we will help you out.