Using the incremental installer for Domino, e.g. upgrade to V11.0.1FP4, often better said mostly, that error message is shown at the end:
"WARNUNG: JVM was not upgraded. Please, see UPGRADE.log and jvmpatcher.log for details."
The upgrade looks like it works, but not upgrading the JVM might end in security and functional issues.
Usually the best way to solve is to fully deinstall Domino, then start a fresh installation plus incremental install. Very anmoying and very time consuming!
There are also several forum discussion about that, but nothing really helpful. And at the end it's worth to search for workarounds, instead of having the installer work.
So, I want, if that this old R8 bug (I think) gets fixed!