Event ID 236 on a Hyper-V server that has SR-IOV enabled on a VM in Windows Server
This article provides a solution to an Event ID 236 that occurs on a Hyper-V server that has SR-IOV enabled on a VM in Windows Server.
Applies to: Windows Server 2016, Windows Server 2019
Original KB number: 4136996
Symptom
On a Windows Server 2016, a Windows Server 2019, a Windows Server, version 1903, or a Windows Server, version 1909 computer that has Hyper-V role enabled, there's a guest virtual machine (VM) that is running Windows Server, and the VM has Single Root I/O Virtualization (SR-IOV) enabled. When the VM or the computer is restarted, event ID 236 is logged in the System log.
The event may have description that resembles the following example:
Failed to allocate virtual function for NIC (Friendly Name: Network Adapter), status = {Drive Not Ready}
Cause
Event 236 is logged when the user-mode process tries to allocate a virtual function before the VM and the host communication channel is established.
More information
The user mode process will retry to enable I/O Virtualization at a later stage in few moments. You can verify the IOV VF function by using the PowerShell cmdlet Get-NetAdapterSriovVf.
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