Opening a console to a virtual machine fails with the error: Unable to connect to the MKS: Console access to the virtual machine cannot be granted since the connection limit of 0 has been reached (2015407)

Symptoms

When you open the console of a powered on virtual machine from vCenter Server or directly on the ESXi/ESX host, you see a black screen with a message at the top of the console screen similar to:

Unable to connect to the MKS: Console access to the virtual machine cannot be granted since the connection limit of 0 has been reached.

Cause

The issue occurs because the limit on the number of simultaneous console connections set in the vSphere Web Client impacts the vSphere client console connection limit.

Resolution

To resolve this issue, deselect Limit the number of simultaneous connections to this Virtual Machine on the affected virtual machine.

 

To deselect Limit the number of simultaneous connections to this Virtual Machine:  

1. Open a session to the vSphere Web Client.
   
   https:// vcenter_server_name:9443/vsphere-client
   
2. After connecting, right-click the affected virtual machine.
3. Click Configuration > Edit Settings.   
4. Click VM options.
5. Click VMware Remote Console Options, then deselect Limit the number of simultaneous connections to this Virtual Machine.
6. Click OK.
7. Open a new console window to the virtual machine in the vSphere Client to verify.

To work around this issue, add an entry to the configuration parameters of the virtual machine.

 

To add an entry to the configuration parameters of the virtual machine:

1. Power off the virtual machine.
2. Right-click the affected virtual machine and click Edit Settings.  
3. Click the Options tab, then click General under Advanced.
4. Click Configuration Parameters.
5. Look for an entry named RemoteDisplay.maxConnections:
   
   
   • If the entry exists, set the Value to 1 or higher.
   • If the entry does not exist, click Add Row to add the parameter. The parameter details are:
     
     Name: RemoteDisplay.maxConnectionsValue: 10
     Note: Value can be set to 1 or more.
     
6. Power on the virtual machine.

Source:-

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2015407