I guess this is a known issue, but it's the first time we've encountered it.
Not really related to pumpkins, but that may be the only fun patch around.
SQL Server 2008 r2, clustered, default instance, service pack 2 fails.
We've succesfully patched 4 named instances on two other clusters with no issues, but the default instance proved to be a problem.
Look in the summary.txt for the error, which will eventually lead to another log file (ours was detail.txt).
SQLEngine: : The source DLL file is 'c:\Program Files\Microsoft SQL Server\MSSQL10_50.<instance_name>\MSSQL\Binn\SQSRVRES.DLL' and the target is 'C:\Windows\system32\SQSRVRES.DLL'.
SQLEngine: : File versions : ['c:\Program Files\Microsoft SQL Server\MSSQL10_50.<instance_name>\MSSQL\Binn\SQSRVRES.DLL':2009.2009.2500.0], ['C:\Windows\system32\SQSRVRES.DLL':2009.2009.1600.1].
SQLEngine: : Upgrading resource type 'SQL Server' using resource for instance '<instance_name>' as reference ...
Slp: Configuration action failed for feature SQL_Engine_Core_Inst during timing ConfigRC and scenario ConfigRC.
Copied the file SQSRVRES.DLL from C:\Program Files\Microsoft SQL Server\MSSQL10_50.<instance_name>\MSSQL\Binn\ to C:\Windows\System32\ and started the service pack again.
The Other error is:
2.2 Setup Might Fail if SQAGTRES.dll Is Locked by Another Process
Issue: A SQL Server setup operation might fail with this error: Upgrading of cluster resource C:\Program Files\Microsoft SQL Server\MSSQL10_50.<Instance name>\MSSQL\Binn\SQAGTRES.DLL on machine <Computer name> failed with Win32Exception. Please look at inner exception for details. The root cause is that C:\Windows\system32\SQAGTRES.DLL is locked by another process and Setup was not able to update it.
Workaround: Rename C:\Windows\system32\SQAGTRES.DLL to a temporary name such as C:\Windows\system32\SQAGTRES_old.DLL, and then select the Retry option on the setup error message. That will allow Setup to continue. After a reboot, you can delete the temporary file C:\Windows\system32\SQAGTRES_old.DLL