While starting a virtual machine (VM) from saved state on my Windows 10 laptop with Client Hyper-V, the following error message popped up and the VM itself did not power on.
An error occurred while attempting to start the selected virtual machine(s).
‘<VMName>‘ failed to change state.
The error itself did not explain a lot why the startup from saved state was failing, but in the Event Viewer and more specific in the Hyper-V event logs (tap the Windows key + R to open Run, type eventvwr in the empty box and tap OK. When opened go to Applications and Services Logs – Microsoft – Windows – Hyper-V-Worker – Admin) Event 3326 was shown, which showed a lot more.
The Virtual Machine ‘VM-W8-HOME’ failed to start because there is not enough disk space. The system was unable to create the memory contents file on ‘C:\_VM\VM-W8-HOME\Virtual Machines\CB9D8995-F1FC-4349-9C35-7728F5B90245’ with the size of 7340 MB. Set the path to a disk with more storage space or delete unnecessary files from the disk and try again. (Virtual machine ID CB9D8995-F1FC-4349-9C35-7728F5B90245)
The error indicates that not enough free space is available on the host which causes problems to start the VM. The View in Disk Management (tap the Windows key + R to open Run, type diskmgmt.msc in the empty box and tap OK) indeed shows that the C: drive only has 2 % free, which is not sufficient to start the VM.
After determining that the error was caused by a lack of disk space, I cleaned up my C: drive by deleting some unnecessary and temporary files, to free up some more space (at least 4096 MB which equals the amount of virtual memory of the VM). As a result, the VM started up again.
To start a VM from saved stated the amount of free disk space should at least equals the amount of virtual memory allocated to the VM.
For example, if your VM has 4096 MB of virtual memory assigned, you should have at least 4096 MB available on the drive. If you do not have enough disk space available you should free up some space to be able to start the VM.
As a recommendation you should always keep at least 10 – 20 % of free disk space available.