CM12 - upgrade of a client to SP1, fails with error: MicrosoftPolicyPlatformSetup.msi installation failed. Exit code 1603

You may face an issue, where you have a CM12 environment and on one of your servers/clients (i.e. Windows Server 2008), the upgrade of the clients to SP1, do not work as expected and fails with the error:
MicrosoftPolicyPlatformSetup.msi installation failed. Exit code: 1603.

In that case, you need to look for any hints in the following log files: ccmsetup.log, clientmsi.log, or C:\WINDOWS\ccmsetup\MicrosoftPolicyPlatformSetup.msi.log

Additionally, if you check the Application.log on the affected client you may see errors like these:

Error WMI 4 None
Error 0x80041002 encountered when trying to load MOF C:\WINDOWS\SYSWOW64\CCM\CACHE\BAK0006D.1.SYSTEM\CCM_ISV.MOF while recovering .MOF file marked with autorecover.

Or if you check the System.log, you may find lines like these:

Warning GroupPolicy (Microsoft-Windows-GroupPolicy) 1090 None
Windows failed to record Resultant Set of Policy (RSoP) information, which describes the scope of Group Policy objects applied to the computer or user.
This could be caused by Windows Management Instrumentation (WMI) service being disabled, stopped, or other WMI errors. Group Policy settings successfully applied to the
computer or user; however, management tools may not report accurately.

They all show that, something is going wrong with this client's WMI (probably some corruption). In that case, these are the resolution steps:

Re-register all WMI modules with the following commands (can be executed as a batch file or individually from the command prompt):
[* This batch file is for Windows XP&Windows Server 2003 operation system. For Windows 7 & Windows Server 2008 operation system, please run this batch file with the Run as administrator option.]. 

@echo off
sc config winmgmt start= disabled
net stop winmgmt /y
%systemdrive%
cd %windir%\system32\wbem
for /f %%s in ('dir /b *.dll') do regsvr32 /s %%s
wmiprvse /regserver
winmgmt /regserver
net start winmgmt 

Recompile all MOF and MFL files by running the following command in the %windir%\system32\wbem directory: for /f %s in ('dir /b *.mof *.mfl') do mofcomp %s 
Reinstall the client .