Citrix Xenserver 6.0 fails update pre-check when applying updates

A while back I upgraded my Xenserver 5.6 FP1 servers to Xenserver 6.0, the upgrade was very smooth, well so I thought. Today I had scheduled some time to apply the 4 Xenserver 6.0 hotfixes currently available but hit a few snags along the way.

When I went to upload the new hotfixes, 1 of my Xenserver complained that pre-check 5 of 5 had failed, the exact error message was as below:

SERVERNAME: The update precheck stage failed: prerequisite updates are missing.

I also noticed the server was in a permanent update pending state (as can be seen from the arrow icon below), even though I hadn't initiated an update.

 

Upon further investigation I found the server was still trying to install old Xenserver 5.6 updates that I never installed before upgrading the server, which was in turn blocking the new updates from installing. This can be caused by not installed updates on the pool master first, but in my case the servers are not in a pool.




Resolving the problem

Fortunately the problem is (or was in my case) quite easy to fix.

1. Open Xencenter, select the server in question and click the console tab.

2. Issue the "xe patch-list" command, this command will give you a list of pending or installed patches.
xe patch-list

3. For every patch with a "name-description" containing 5.6, obtain the UUID (for example in the above image the UUID is "17fde43e-0a5e-48ac-8b85-cf6ed9c6344d"), then issue a "xe patch-destroy" command.

xe patch-destroy uuid=<UUID>

for example:
xe patch-destroy uuid=17fde43e-0a5e-48ac-8b85-cf6ed9c6344d

4. You may or may not need to restart the server but if you have been successful the "down arrow" icon next to the server name will disappear and return to a "green circle" (as per the image below).

This simple fix should resolve your problems, although some users on the Citrix forums have reported similar problems that are more serious. In most cases these users have migrated the data to another server and rebuilt the server.

I still don't know how this problem was caused, but I suspect I simply had pending updates on this particular server before I upgraded it to Xenserver 6.0 that became "stuck".