While trying to upgrade with Software Update Manager (SUM), the tools stop with an error in phase MOD_SELROADMAP/SUMCHK_EXTBUILD.
With a short message:
"Last error code set: Environment variable 'dbms_type' does not exist"
I have also attached the screenshot below:
To resolve this issue please check whether all the steps followed by you for upgrading is correct according to SUM guide. Also review some points listed below:
And if the points mentioned above are correct and you still facing the issue than please check for newer SUM patch released, reset the SUM according to SUM guide steps and restart with latest correct patch