Resolving Error Virtual Machine Manager Error 12700

Posted by ciscog33k on

If you’re trying to add a logical switch and get there could be a couple reasons why. The full text of the error is follows

Error 12700: VMM Cannot complete the host operation on the  server because of the error: Failed while modifying virtual Ethernet connection settings. Unknown error (0x8005)

I’m not sure if this will be a common configuration, but due to Equallogic best practices for hyper-v hosts, I wanted to create two separate logical switches, each bound to a different physical adapater and different physical switch, but bound to the same logical network in VMM. It turns out that order of operations matters very much here. What I did to encounter the error was as follows:

  1. I created a logical network called “iSCSI Logical Network”
  2. Created  native port profile called “iSCSI Uplink Port Profile”
  3. Created logical switch “logSwitch-iSCSI1”, which used the iSCSI uplink port profile and consequently the iSCSI logical network.
  4. Created new logical switch “logSwitch-iSCSI1” on the Hyper-V host and assigned physical NIC “iSCS1_NIC” to it
  5. I applied changes to test it worked
  6. It did, so I repeat steps 3-5 by creating logSwitch-iSCSI2 with “iSCSI2_NIC”. Step 5 is where I encountered the error.

If I went to another host that didn’t have “logSwitch-iSCSI1” created already, “logSwitch-iSCSI2” added without incident. The problem was clearly related to adding the second “logSwitch-iSCSI1” to a host that already had one that was connected to the same logical network.

It turns out that the solution to this is simple, but not exactly obvious. All you have to do is delete the first logical switch you created on your host and then add them both back at the same time, instead of one at a time. I’m not sure why this happens but it seems like this is probably a pretty easy problem to encounter among people doing initial configuration for the first time. You create the first to make sure your config works, and once that is confirmed, add the second. Nope, you have to do both at the same time in VMM or you’ll get 12700 every time.

I have seen this rather generic error be caused by a second type of problem as well. Many people experimenting with Hyper-V and VMM might have initially configured network teams on their hosts via Server 2012 Teaming. Make sure the teams are properly deleted before trying to configure a logical switch using the same network cards. It will let you try to apply the configuration and doesn’t really give you a helpful error message, just the 12700 error.

 

Leave a comment