Unable to connect to the MKS: Internal Error

[unsichtbare]

After adding hosts to vCenter, when I try to upen the VMRC, I get the error: Unable to connect to the MKS: Internal Error

First off, it is not the usual DNS resolution of Host IP addresses MKS Error! This is something entirely different.

One unusual thing in the manifestation of this problem is that by powering off (fully off, not a restart) and then powering on the VM in question, the console will work for that VM, but the console will continue to malfunction for other VMs on the same host until those VMs are vMotioned or completely power-cycled!

Here is the workflow:

1. I stand-up a new ESXi (patched and firmwared to latest updates)
2. I build a Windows or Linux VM to serve DNS and/or be an AD Domain Controller
3. I install the VCSA (or Windows vCenter)
   1. I log in and test forward and reverse resolution for all hosts on the Broadcast Domain
4. I add the ESXi Host (and any other hosts) to vCenter
5. I try to open a VMRC and get the MKS error!

This is a minor issue except for the VCSA itself!

Any ideas?

[greco827]

Port 902 is open from where you are launching the console to the VCSA?

[linotelera]

‌Hi

did it happens in web client too? what about esxi logs?

[praveenkv]

I have faced same issue for many VMs in my environment, issue got fixed once Port 902 is opened for MKS : Internal error.

--- If you find this or any other answer useful please mark the answer as correct or helpful ---

[unsichtbare]

Yes, 902 is open. The VMRC works VMs after a complete power-cycle for the VM. If this were a network or DNS issue, power-cycling the VM would not help.

Thanks for the thought!

[unsichtbare]

I hate to use the Web Client under any circumstances, but it does represent a valid test.

The Web Client console never connected and will not re-connect, and gives the message: "The console has been disconnected. Close this window and re-launch the console to reconnect."

This is what the Windows client for the same VM looks like (prior to a power-cycle of the VM):

This is what the Windows client looks like to another VM on the same host (but only after I powered the VM off and back on):

Any help appreciated!

[greco827]

Might need to flush dns...

[unsichtbare]

Already done!

[greco827]

That didn't help either?

[unsichtbare]

It is clearly not a DNS or network connectivity issue.

I can use the VMRC just fine before I add the host to vCenter. After I add the host to vCenter, the VMRC will not work for VMs that were powered-on at the time I added the host.

This is a new symptom of vSphere 6  and did not present in previous versions!

Telnet to host:

Ping by hostname:

[mohdhanifk]

These links may help:

VMware KB: Troubleshooting virtual machine console and MKS issues in the vSphere Client

“Unable to connect to the MKS: Internal Error” when connecting to the virtual machine console - www....

[JonTom12 · Accepted solution]

I had the exact same symptoms as you. Fortunately I was able to find this link:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=211654...

Looks like we either need to power off and back on, suspend and power back on, or vMotion to another host in order to resolve. I guess it has to do with generating a new SSL cert when joining a host to vCenter? I've verified that at least the first two options work, so I hope this answers your question.

[suvrobhattachar]

Since the server is already responding to PING with Host name so DNS resolution is working fine .

Have you tried to patch the ESXi Host with latest update and reboot it to access the Host .

[unsichtbare]

Thanks JustTom12!

That's the KB I have been looking for for weeks. Now I at least know why and have an acknowlegement from VMware about the issue.

[capcom700]

Hi There...

I see this problem in many user when I go to do some support in the environment and I see, they can connect by RDP fine, but when they are trying to use the console from vmware they got the same problem.

Unable to Connect the MKS: Internal error

This is another method to solve this error , I hope will be helpful to you.

1-Turn off the VM.

2-Tab VM>Edit setting

3-In the Tab Hardware, Go to Video Card

4-and select Auto-detect setting

5- click OK, and Turn ON

and that all, just 5 step.

I do the same step in other end user, and work fine.

let me know if that working for you.

Thanks and regards

by.

Edgar Bueno

:smileycool:

[newuserguy]

@ capcom700capcom700

Boom! Worked like a charm on 6.0! stupid video cards were all configured as "Specify custom settings"...not sure why, I didn't change anything.

Great tip!

[capcom700]

Great!!:smileycheck:

Thanks for the good news!

I hope that simple step, can help many environment for vmware when the end user do a upgrade to the version 6.x or when is just installed.