Okular ne peut pas lire les fichiers pdf

J'ai récemment installé Okular sur mon Ubuntu 14.04.

Le problème est que lorsque j'ouvre des fichiers pdf, okular me donne l'erreur "Impossible de trouver un plugin capable de gérer le document transmis."

Quand j'ai couru Okular par Terminal, c'est le message que je reçois.

admin@me:~$ okular ex01.pdf
okular(14100)/kdeui (KIconLoader): Error: standard icon theme "oxygen" not found! 
okular(14100)/kdeui (KIconLoader): Error: standard icon theme "oxygen" not found!

okular(14100) KPixmapSequence::Private::loadSequence: Invalid pixmap specified. 
okular(14100) KPixmapSequence::Private::loadSequence: Invalid pixmap specified. 
okular(14100) KPixmapSequence::frameSize: No frame loaded 
okular(14100) KPixmapSequence::Private::loadSequence: Invalid pixmap specified. 
okular(14100) KPixmapSequence::frameSize: No frame loaded 
okular(14100) KPixmapSequence::Private::loadSequence: Invalid pixmap specified. 
okular(14100) KPixmapSequence::frameSize: No frame loaded 
okular(14100) KPixmapSequence::Private::loadSequence: Invalid pixmap specified. 
okular(14100) KPixmapSequence::frameSize: No frame loaded 
okular(14100) KPixmapSequence::Private::loadSequence: Invalid pixmap specified. 
okular(14100) KPixmapSequence::frameSize: No frame loaded 
okular(14100) KPixmapSequence::Private::loadSequence: Invalid pixmap specified. 
okular(14100) KPixmapSequence::frameSize: No frame loaded 
okular(14100): No ksycoca4 database available! 

okular(14100)/kdecore (trader) KServiceTypeTrader::defaultOffers: KServiceTypeTrader: serviceType  "okular/Generator"  not found 
okular(14100)/kdecore (KConfigSkeleton) KCoreConfigSkeleton::writeConfig:
okular(14100)/kdecore (KConfigSkeleton) KCoreConfigSkeleton::writeConfig:
okular(14100)/kdecore (KConfigSkeleton) KCoreConfigSkeleton::writeConfig:
okular(14100)/kdecore (KConfigSkeleton) KCoreConfigSkeleton::writeConfig:
okular(14100)/kdecore (KConfigSkeleton) KCoreConfigSkeleton::writeConfig:
okular(14100): No ksycoca4 database available! 

okular(14100)/kdecore (trader) mimeTypeSycocaServiceOffers: KMimeTypeTrader: mimeType "application/pdf" not found 
okular(14100): No ksycoca4 database available! 

okular(14100)/kdecore (trader): KMimeTypeTrader: couldn't find service type "okular/Generator" 
Please ensure that the .desktop file for it is installed; then run kbuildsycoca4. 
okular(14100)/okular (app) Okular::Document::openDocument: No plugin for mimetype '"application/pdf"'.
okular(14100): Couldn't start knotify from knotify4.desktop:  "KLauncher could not be reached via D-Bus. Error when calling start_service_by_desktop_path:
The name org.kde.klauncher was not provided by any .service files
" 
okular(14100)/kdeui (KNotification) KNotification::slotReceivedIdError: Error while contacting notify daemon "The name org.kde.knotify was not provided by any .service files" 

X Error: BadWindow (invalid Window parameter) 3
Major opcode: 20 (X_GetProperty)
Resource id:  0x2a0002e
okular(14110) KPixmapSequence::Private::loadSequence: Invalid pixmap specified. 
okular(14110) KPixmapSequence::frameSize: No frame loaded 
okular(14110) KPixmapSequence::Private::loadSequence: Invalid pixmap specified. 
okular(14110) KPixmapSequence::frameSize: No frame loaded 
okular(14110) KPixmapSequence::Private::loadSequence: Invalid pixmap specified. 
okular(14110) KPixmapSequence::frameSize: No frame loaded 
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 20 (X_GetProperty)
Resource id:  0x2a0001d
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 20 (X_GetProperty)
Resource id:  0x2a0001d

Je serais très apprécié pour toute suggestion visant à résoudre ce problème. Merci beaucoup :)

C'était assez ennuyeux, mais:

sudo apt-get install kdelibs5-plugins kdelibs5-data oxygen-icon-theme

J'ai eu le même message d'erreur. Dans mon cas, Okular a été installé avec sudo, et les dépendances de KDE ont été installées dans le dossier d'accueil sous .kde, mais avec root comme propriétaire et groupe.

J'ai changé en exécutant:

sudo chown -R youruser .kde    
sudo chgrp -R youruser .kde

puis cela a fonctionné normalement.

Selon les notes de publication de Linux Mint dans la section "Problèmes avec les applications KDE"

Si vous rencontrez des problèmes avec les applications KDE (Okular, Gwenview, KStars..etc), exécutez la commande suivante:

apt install kdelibs-bin kdelibs5-data kdelibs5-plugins

Remarque: Ces problèmes n'affectent pas l'édition de KDE. Une régression dans KDE 4.14 empêche ces applications de fonctionner correctement hors de la boîte en dehors de KDE.

Ouvrez Synaptic Package Manager et recherchez kde-core-devel

Installez tous les packages sous la version 4:4.14.2-0ubuntu1~ubuntu14.04~ppa1. Ensuite, recherchez oxygenet installez le thème d'icône d'oxygène.