Btw, this is for openSUSE 10.3.

> The binary provided by opensuse's repository fails to open any pdf files.

Then please report the problem to OpenSUSE. I can do exactly nothing for broken distro packages.

I'm getting this same error, from a subversion checkout; my entire kde4 is from svn trunk, except for qt, which is the real qt-4.4.2 release.  I have poppler-0.6.3 (built from source), and it doesn't appear that okular is linked against it.  Could that be an issue?  cmake says that it finds poppler-qt4, so I would assume that it's being used, but I cannot open pdfs.  The two debug lines of interest are:

okular(20796)/kdecore (trader) KMimeTypeTrader::query: query for mimeType  "application/pdf" ,  "okular/Generator"  : returning  0  offers
okular(20796)/okular (app) Okular::Document::openDocument: No plugin for mimetype '"application/pdf"'.

Also, probably unrelated, the error message that pops up to tell me that okular cannot open my pdf takes about 30 seconds before I can click on the Ok button.  I'm seeing that a lot with my kde4 setup though, so it's probably not associated with the issue of being unable to open pdfs.

@jay (comment #3):
Please read http://okular.kde.org/faq.php#OkulartellsmetherearenopluginsinstalledWhatcanIdo

Ok, so when kbuildsycoca4 doesn't work, what can I do to continue trying to solve my problem?  In dolphin, the preview of my pdfs works just fine, but I cannot actually view them in okular.  I just wiped out my .kde directory, did full svn up of everything and rebuilt my kde4 system, rebooted, and logged back in to a fresh kde4 environment.  Okular is still not working.

As an addendum to the previous response, when I run kbuildsycoca4, I get a lot of lines like

kbuildsycoca4(9190) KBuildServiceFactory::populateServiceTypes: "phononbackends/xine.desktop" specifies undefined mimetype/servicetype "audio/8svx"                                  

Is the undefined mimetype stuff bad?  I'm probably getting around a hundred lines of that, although application/pdf does not appear in that list.

(In reply to comment #4)
> @jay (comment #3):
> Please read
> http://okular.kde.org/faq.php#OkulartellsmetherearenopluginsinstalledWhatcanIdo

Even with that, Okular is still broken for me:
$ kbuildsycoca4 --noincremental
kbuildsycoca4 running...                                
kbuildsycoca4(22460) KBuildMimeTypeFactory::createEntry: Missing <comment> field in  "/opt/kde4/share/mime/text/plain.xml"                                                                                                                  
kbuildsycoca4(22460) KBuildMimeTypeFactory::createEntry: Missing <comment> field in  "/usr/share/mime/application/x-gip.xml"                                                                                                                
kbuildsycoca4(22460) VFolderMenu::loadDoc: Parse error in  "/home/esandall/.config/menus/applications-merged/wine-Programs-Turbine-Dungeons & Dragons Online - Stormreach.menu" , line  15 , col  43 :  "letter is expected"                
kbuildsycoca4(22460) KConfigGroup::readXdgListEntry: List entry MimeType in "/usr/share/applications/kde/ark.desktop" is not compliant with XDG standard (missing trailing semicolon).                                                      
kbuildsycoca4(22460) KConfigGroup::readXdgListEntry: List entry Categories in "/usr/share/applications/kde/kontactdcop.desktop" is not compliant with XDG standard (missing trailing semicolon).                                            
kbuildsycoca4(22460) KConfigGroup::readXdgListEntry: List entry Categories in "/usr/share/applications/gvim.desktop" is not compliant with XDG standard (missing trailing semicolon).                                                       
kbuildsycoca4(22460) KConfigGroup::readXdgListEntry: List entry MimeType in "/usr/share/applications/smplayer.desktop" is not compliant with XDG standard (missing trailing semicolon).                                                     
kbuildsycoca4(22460) KConfigGroup::readXdgListEntry: List entry Categories in "/usr/share/applications/vim.desktop" is not compliant with XDG standard (missing trailing semicolon).                                                        
kbuildsycoca4(22460) KConfigGroup::readXdgListEntry: List entry Categories in "/usr/share/applications/firefox.desktop" is not compliant with XDG standard (missing trailing semicolon).                                                    
kbuildsycoca4(22460) KConfigGroup::readXdgListEntry: List entry Categories in "/usr/share/applications/cacaview.desktop" is not compliant with XDG standard (missing trailing semicolon).                                                   
kbuildsycoca4(22460) KConfigGroup::readXdgListEntry: List entry Categories in "/usr/share/applications/gcalctool.desktop" is not compliant with XDG standard (missing trailing semicolon).                                                  
kbuildsycoca4(22460)/kdecore (KService) KServicePrivate::init: The desktop entry file  "/opt/kde4/share/applications/kde4/koffice.desktop"  has Type= "Application"  but no Exec line

$ okular 4117172793_1.pdf
okular(20243): Attempt to use QAction "bookmark_action_0" with KXMLGUIFactory!
okular(20243)/okular (app) Okular::Document::openDocument: No plugin for mimetype '"application/pdf"'.

$ okular --version
Qt: 4.5.0
KDE: 4.2.2 (KDE 4.2.2)
Okular: 0.8.2

$ find . -name "okular*" -exec rm -rf {} \;
./.kde4/share/config/okularrc
./.kde4/share/config/okularpartrc
./.kde4/share/apps/okular

Still no luck. The issue, at least for me, was popper wasn't built with '--enable-poppler-qt4' before building kdegraphics. Rebuilding poppler correctly fixed this for me.

I'm having the same problem. I compiled from SVN, so it's not a distro problem. Poppler-qt4 is installed and I did what comment #4 suggests without success.