Fix: Ethernet Switch Error Virtual machine failed to start in Hyper-V 2019

Sometimes due to the result of system or hardware changes, a virtual machine fails to start properly usually because it cannot read the existing system resources on your computer. There are variations of the issue where virtual machines can’t be started because of the Ethernet virtual switch errors.

The full error message is:

An error occurred while attempting to start the selected virtual machine(s). Synthetic ethernet Port: Error Insufficient system resources exist to complete the requested service. Failed to allocate resources exists to complete resources to a virtual network. The Ethernet switch may not exist.

The error code implies there is an issue with one or more virtual switches that are assigned to the virtual machine(s). The virtual switch may be deleted from the Hyper-V host or it is not working properly.

There are three types of virtual switches; Private switch which provides only communication between the virtual machines, Internal switch which provides communication between host and virtual machines and External which provides communication between virtual machines and the rest of the network.

We need to identify which virtual switch has a problem and then fix it accordingly. It is also necessary to investigate if the same problem exists on all virtual machines that are using a certain virtual switch or only on an individual virtual machine.

This issue is not only related to Hyper-V 2019 but also to previous versions of Hyper-V Servers and Hyper-V Clients. We will simulate the same problem on Hyper-V 2019 and a virtual machine with the Windows Server 2019 installed.

In the first step, we will check if the Configuration error is shown within the virtual machine that has a problem.

1. Open Hyper-V Manager on Windows Server (2012, 2012 R2, 2016 or 2019) or Windows Client (8, 8.1 and 10)
2. Right-click on the virtual machine and then select Settings
3. Under Hardware list click on Network Adapter.
   You see on the screenshot below that this Network Adapter has a Configuration Error. We do not see much information here, so we will jump into Hyper-V Manager settings.
4. Close the window, select the host, right-click on it, and then choose Virtual Switch Manager.
5. Under Virtual Switches, click on the network virtual switch that is assigned to a virtual machine that has a problem with Network Adapter.
   In our case, it is an adapter called LAN. We can see that LAN is an external adapter that is using physical network card Realtek USB GbE Family Controller and it provides communication between virtual machines and the rest of the network.
6. Once we identify what network card is used for virtual switch, the next step would be to verify if the network card is connected and working properly. Please navigate to the Control Panel\Network and Internet\Network Connections and check if the network card is enabled or disabled or connected to the network.

If the network card is enabled and connected to the network, please check the drivers. If this issue has occurred once you have updated your network card driver, consider doing a rollback. This can be done using the Device Manager. You can read more in the Solution 1.