Today I experienced the error shown in the title of this post while opening the VM console of some VMs. This short post will help you solve this issue on short and long term.

This post was updated on the 30th of April 2014.

The environment consists of four ESXi hosts, running on vSphere 5.5 build 1331820 (Vanilla HP image). The hosts have been running for about 2 weeks now, so be sure to check your console access after this time if you’re running on the same build and want to prevent complaints 🙂

Not all VMs showed this issue, so it had to do with the particular ESXi host they were running on.

After moving the VMs to a different host, the VM console was able to open up for those VMs.
Rebooting the ESXi host they were running on solved it for that particular host.

This is a known issue and described by the following VMware KB article.

As VMware suggests, you should update your environment and increase the build to 1474528 or higher.

Update: 2014-04-30

If you are running HP ProLiant Gen8 servers in your environment, and are using the HP Customized ISO to install your machines with, you will probably still have this issue. This has to do with a bug in the HP AMS service running on your ESXi box. To (temporarily) fix this issue, you should SSH into your box, and restart the service using the following command:

./etc/init.d/hp-ams restart

After restarting the service, your VM console access will be available. No restart of the host is required and your VMs will keep running. When I have found, implemented and tested the permanent fix, I will update this post again.