Detail.txt:

Cannot execute a program. The command being executed was „C:\Windows\Microsoft.NET\Framework64\v2.0.50727\csc.exe“ /noconfig /fullpaths

Solution:
Extract the Update/Upgrade File to a Folder on Drive C: and Start the setup from there.

For SQL 2008:

Take SQL Server (XXX) Resource offline:

>cluster res „SQL Server (XXX)“ /OFFLINE

Remove Registry Check:

> cluster res „SQL Network Name (nnnnn)“ /removecheck:“SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL10.XXX\MSSQLServer“

Do whatever you have to configure

Add the Registry Check:

cluster res „SQL Network Name (nnnnn)“ /addcheck:“SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL10.XXX\MSSQLServer“

Take the Resources Online:

cluster res „SQL Server (XXX)“ /ONLINE

cluster res „SQL Server Agent (XXX)“ /ONLINE

„SQl Server (XXX)“ is the Name of your SQL Resource in Failover Cluster Management, where XXX is a possible Instancename

SetValue:

\Package.MaximumErrorCount 10

\Package.ForceExecutionResult 3