It is useful to diagnose issues with the repository of OEM as it doesn’t need the OMS to be running to use it.
The Oracle document 763072.1 (Oracle Enterprise Manager Grid Control Release Notes for Linux and Windows 10g Release 5) suggests upgrading the EMDIAG kit before performing a general OEM upgrade (it's in the OEM pre-upgrade tasks list).
Follow the steps in document 421499.1 to install the EMDIAG kit into the C:\ directory (you should see the old one already installed there).
Follow the process in the document for upgrading the EMDIAG kit and check the Windows environment variable for the EMDIAG_HOME value.
Once installed, use the “repvfy -version” command in the %EMDIAG_HOME%\bin directory to verify the current installed OEM software.
To use EMDIAG, set your OracleHome from the command line:
Change to the EMDIAG_HOME bin directory and run repvfy:
Now fix the errors where possible (generic operations that EMDIAG can perform to fix common problems):
Some of the problems cannot be fixed automatically.
You can get more details by running verify with greater detail:
repvfy verify TARGETS -level 9 -detail
NOTE: You may want to redirect to a text file in Windows (> c:\TARGET_details.txt).
The detailed view may open a can of worms for you.