IBM released Domino 9.0.1 Fixpack 3 Domino 9.0.1 Fixpack 3 today. As always I went into the problem when trying to install it. It said that my version is not the one expected which was caused by the prior installed Interim Hotfix 384. So this post is basically a reminder for me to uninstall any Hotfixes before installing a real Fixpack.
Run the installer of the Hotfix again and choose "Downgrade" to the prior version (in that case FP2).
After that you are able to install the new Fixpack without any trouble.
BUT...
For some reason I had a problem after installing the FP3 on my Win64 machine. When starting the server as an application (via shortcut) it says "nsdhelp.dll" is missing. I don't know if this is a bug in the FP3 installer (to remove it but not substitute it) or is caused by other cirumstances. If you have the same problems and a clue how to fix it, then please leave a comment. I worked it around by copying the DLL from another machine to the Domino program directory. The server started normally again.
Then another problem: HTTP won't start anymore: "cannot load resource file - exiting".
I reinstalled the whole bunch completely (Domino and FP3 directly afterwards) and now it runs.
My question: is that a Win64 version problem as I never had any trouble on Linux or were the latest Fixpacks just buggy?