If you are suddenly (June 2011) unable to Scan for Updates or Remediate VMware ESX 3.5 Hosts, you may be without ESX350-201012410-BG (VMware KB 1030001). When running ESXUpdate via SSH on the host, you’ll receive an Integrity Error that includes “Signature 0BFA1C860F0B0A6CF5CD5D2AEE7835B14789B619: keyExpired: 4789B619″
To resolve this, you’ll need to bypass the Signature Requirement for patching so the new Secure Key Patch can be applied. To do this, connect via SSH to the host, and run the following command.
esxupdate -d http://patchdepoturlhere --nosig update
This will install all updates and reboot the host, so be sure it’s in maintenance mode prior to running the command. After the host has been patched in this method, you’ll be able to use the VUM GUI again.