VMWare Server is a great product for running multiple virtual machines on top of a host system (in my case Windows 2003 Server) but the Web Interface is sluggish and poorly designed. But for a free product i’m definitely not complaining..

On the weekend while doing some routine maintenance I hit a point where from any machine I was unable to access the Web Interface for any longer than a few seconds before it started returning ‘timed out: cannot communicate with host’ errors. I would be returned to the VMWare login screen, log back in, and immediately get the same error – around and around we go..

I tried to restart the VMware Host Agent Service on the Server machine, briefly be able to connect back in, then the same thing over again. No matter what you did you couldn’t get a connection to the Web Interface for longer than a few seconds before it would stop responding.

Checking the Windows event logs revealed numerous ‘Cannot connect to VMX: c:\virtual machines\{vm name}.vmx’ errors when the VMWare Host Agent Service was trying to start up. Weird..

The problem and solution I found was two fold:

1) I have moved a number of virtual machines over to a new VMware server the day before. These VM’s were scheduled to be autostarted by VMware and it simply could not find them. Seeing how I couldn’t go into the VMware Web Based Console to adjust these settings I had to physically rename the vmautostart.xml file, restart the VMWare Host Agent Service and let it rebuild a new empty autostart config file then go and reconfigure an VM’s you wanted to auto-start with the Server.

The Host Service config files are located normally in “c:\Documents and Settings\Default User\Application Data\VMware” on Windows 2003 Server or “C:\ProgramData\VMware\VMware Server\hostd” on Windows 2008.

2) I have read some time ago on the VMWare forums that this can be due to authentication issues with the VMWare Host Agent Service. I removed the authorization.xml file and restarted the host service allowing it to recreate it. The authorization.xml file is located in the same place.

Restarting up the VMWare Host Agent Service after making these changes allowed the Web Interface to be accessible again. Happy Days! No more ‘cannot connect’ event log entries were created either after this.

Please do make a backup of any files before you start deleting them so you can copy them back if need be!

I hope this helps someone else that has the same problem.