Seeking to fix this error: "Failed while adding virtual Ethernet switch connections."

Question

I am getting the error below when trying ot make modifications to my Hyper-V.
I am trying to add a new Virtual Adaptor.
Hoping someone may have a suggestion on how to fix this.
Error:
New-VMSwitch : Failed while adding virtual Ethernet switch connections.
Failed to connect Ethernet switch port (switch name = 'XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX', port name =
'XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX', adapter GUID = '{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}'): The system cannot
find the file specified. (0x80070002).
The operation failed because the file was not found.
At line:1 char:1
+ New-VMSwitch -Name "LAN1" -NetAdapterName "Ethernet" -AllowManagementOS $True
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (Microsoft.HyperV.PowerShell.VMTask:VMTask) [New-VMSwitch], Virtualizati
   onOperationFailedException
    + FullyQualifiedErrorId : ObjectNotFound,Microsoft.HyperV.PowerShell.Commands.NewVMSwitchCommand

Answer 1

Alex just a quick response to your advice re disabling AV, this did not work for me, after more searching the internet for a solution I found a post from 2013 where one poster offered the advice to go one step further, and it was to remove the AV package
completely, the package in question was KIS2013. I have KIS2015 and figured I would try it as I was getting a little frustrated with the constant failure to create a virtual switch.
Anyway, it worked for me, I removed KIS, rebooted, and the VS was created on the first attempt without any issue. So simply pausing/disabling the AV from within the AV program may not be enough, I suspect that some may work and others not, as in the case
of KIS. I wonder also if you disable the AV services at start-up if this would also work but I did not try it.
Anyway to other people experiencing this issue, I suggest disabling AV first as per Alex's advice, and if this does not work for you then suggest trying to remove the AV before doing anything more drastic like re-installation of OS as I have seen suggested
in more than one place.
Thanks
Mr Bee
--EDIT--
Just wanted to add, it is also worth 'excluding' any Hyper-V folders from the AV engine, I did not try this before removing KIS2015 so it may work without the need to remove your AV product, but on re-install I have now exluded the folders as suggest by
a few folks in various posts...