I was compiling: https://download.kde.org/stable/applications/18.08.0/src/okular-18.08.0.tar.xz Okular installed fine; no compile problem. However had, it can not find something when I try to open a local .pdf file. The error message shown is: "Unable to find the Okular component: The shared library was not found." Could you guys add to this error message WHICH particular shared library was not found? It's hard to google for this if it does not tell me which shared library is needed (or perhaps it is in a non-standard location, though I doubt it). (I compiled everything from source, via prefix /usr/ - so if it is an official tarball, it is simple for me to add it, but without okular telling me more, there is no real way for me to find out) Overall KDE is getting easier to compile and use though - I am confident that okular will soon run too.
Please try to determine what is the directory for KDE plugins in your distribution (just look in which directory the package system of your distribution puts "okularGenerator_poppler.so"). Then put all your installed Okular plugins in the same directory. For example (Mageia, 64-bit), the version which is compiled from source installs plugins in /usr/lib64/plugins/okular, but Okular search them in /usr/lib64/qt5/plugins/okular .
This is not a bug, this is you not knowing how to compile/install. Please hop onto the okular mailing list if you want this kind of technical support.