模式丢失 – Unity Tweak Tool
我理解这与这个问题和这个问题非常相似，但没有一个答案对我有用。 在尝试安装这些问题中提到的软件包时，apt-get会抛出以下错误消息：
Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies. unity-webapps-service : Depends: webapp-container E: Unable to correct problems, you have held broken packages. 当我尝试安装那里提到的依赖项时，我发现越来越多的依赖项。 当我选择“修复损坏的软件包”时，Synaptic软件包管理器会显示错误消息。 我怎样才能解决这个问题？
在此先感谢，如果您需要更多信息，请发表评论。
更新 ：运行apt-cache policy webapp-container unity-webapps-service给出了以下结果：
webapp-container: Installed: (none) Candidate: 0.23+14.04.20140428-0ubuntu1 Version table: 0.23+14.04.20140428-0ubuntu1 0 500 http://gb.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages 0.23+14.04.20140414-0ubuntu1 0 500 http://gb.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages unity-webapps-service: Installed: (none) Candidate: 2.5.0~+14.04.20140409-0ubuntu1 Version table: 2.5.0~+14.04.20140409-0ubuntu1 0 500 http://gb.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages 100 /var/lib/dpkg/status
更新2 ：版本信息：
LSB Version: core-2.0-amd64:core-2.0-noarch:core-3.0-amd64:core-3.0-noarch:core-3.1-amd64:core-3.1-noarch:core-3.2-amd64:core-3.2-noarch:core-4.0-amd64:core-4.0-noarch:core-4.1-amd64:core-4.1-noarch:security-4.0-amd64:security-4.0-noarch:security-4.1-amd64:security-4.1-noarch Distributor ID: Ubuntu Description: Ubuntu 14.04.2 LTS Release: 14.04 Codename: trusty
更新3 ：尝试使用aptitude而不是apt-get安装unity-webapps-service ：
The following NEW packages will be installed: liboxideqt-qmlplugin{a} liboxideqtcore0{a} liboxideqtquick0{ab} libqt5feedback5{a} libqt5multimedia5{ab} libqt5organizer5{ab} libqt5positioning5{ab} libunity-webapps0{a} qtdeclarative5-dialogs-plugin{ab} qtdeclarative5-privatewidgets-plugin{ab} qtdeclarative5-qtfeedback-plugin{a} qtdeclarative5-ubuntu-ui-extras-browser-plugin{a} qtdeclarative5-ubuntu-ui-toolkit-plugin{ab} unity-webapps-qml{a} unity-webapps-service webapp-container{ab} webbrowser-app{ab} 0 packages upgraded, 17 newly installed, 0 to remove and 0 not upgraded. Need to get 26.6 MB of archives. After unpacking 103 MB will be used. The following packages have unmet dependencies: webapp-container : Depends: qtdeclarative-abi-5-2-1 which is a virtual package. libqt5organizer5 : Depends: qtbase-abi-5-2-1 which is a virtual package. qtdeclarative5-dialogs-plugin : Depends: qtbase-abi-5-2-1 which is a virtual package. Depends: qtdeclarative-abi-5-2-1 which is a virtual package. webbrowser-app : Depends: qtdeclarative-abi-5-2-1 which is a virtual package. qtdeclarative5-privatewidgets-plugin : Depends: qtbase-abi-5-2-1 which is a virtual package. libqt5multimedia5 : Depends: qtbase-abi-5-2-1 which is a virtual package. libqt5positioning5 : Depends: qtbase-abi-5-2-1 which is a virtual package. liboxideqtquick0 : Depends: qtdeclarative-abi-5-2-1 which is a virtual package. qtdeclarative5-ubuntu-ui-toolkit-plugin : Depends: qtbase-abi-5-2-1 which is a virtual package. Depends: qtdeclarative-abi-5-2-1 which is a virtual package. The following actions will resolve these dependencies: Keep the following packages at their current version: 1) liboxideqt-qmlplugin [Not Installed] 2) liboxideqtcore0 [Not Installed] 3) liboxideqtquick0 [Not Installed] 4) libqt5feedback5 [Not Installed] 5) libqt5multimedia5 [Not Installed] 6) libqt5organizer5 [Not Installed] 7) libqt5positioning5 [Not Installed] 8) libunity-webapps0 [Not Installed] 9) qtdeclarative5-dialogs-plugin [Not Installed] 10) qtdeclarative5-privatewidgets-plugin [Not Installed] 11) qtdeclarative5-qtfeedback-plugin [Not Installed] 12) qtdeclarative5-ubuntu-ui-extras-browser-plugin [Not Installed] 13) qtdeclarative5-ubuntu-ui-toolkit-plugin [Not Installed] 14) unity-webapps-qml [Not Installed] 15) unity-webapps-service [Not Installed] 16) webapp-container [Not Installed] 17) webbrowser-app [Not Installed] Accept this solution? [Y/n/q/?]
更新4 ： sudo apt-get install qtdeclarative-abi-5-2-1 ：
Reading package lists... Done Building dependency tree Reading state information... Done Package qtdeclarative-abi-5-2-1 is a virtual package provided by: libqt5qml5 5.2.1-3ubuntu15.1 [Not candidate version] libqt5qml5 5.2.1-3ubuntu15 [Not candidate version] E: Package 'qtdeclarative-abi-5-2-1' has no installation candidate
输出sudo apt-get install unity-webapp-container ：
Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package unity-webapp-container
更新5 ： apt-cache policy libqt5qml5输出：
libqt5qml5: Installed: 5.3.0-3ubuntu13~trusty1 Candidate: 5.3.0-3ubuntu13~trusty1 Version table: *** 5.3.0-3ubuntu13~trusty1 0 500 http://ppa.launchpad.net/mscore-ubuntu/mscore-stable/ubuntu/ trusty/main amd64 Packages 100 /var/lib/dpkg/status 5.2.1-3ubuntu15.1 0 500 http://gb.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages 5.2.1-3ubuntu15 0 500 http://gb.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
输出sudo apt-get install webapp-container ：
Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies. webapp-container : Depends: qtdeclarative-abi-5-2-1 Depends: unity-webapps-qml but it is not going to be installed Depends: webbrowser-app (= 0.23+14.04.20140428-0ubuntu1) E: Unable to correct problems, you have held broken packages.
我会冒险并留下回应。
一个主要问题似乎是PPA ppa：mscore-ubuntu / mscore-stable。 使用此PPA，您无法使用所需版本的libqt5qml5
因此，请使用以下命令删除PPA。
sudo ppa-purge ppa:mscore-ubuntu/mscore-stable
之后
sudo apt-get install -f
最后
sudo apt-get install unity-webapps-service
问题出在哪儿？
命令apt-cache policy libqt5qml5返回以下内容。 PPA ppa：mscore-ubuntu / mscore-stable为libqt5qml5安装较新版本（5.3.0），但qtdeclarative-abi-5-2-1需要精确版本5.2.1。
libqt5qml5: Installed: 5.3.0-3ubuntu13~trusty1 Candidate: 5.3.0-3ubuntu13~trusty1 Version table: *** 5.3.0-3ubuntu13~trusty1 0 500 http://ppa.launchpad.net/mscore-ubuntu/mscore-stable/ubuntu/ trusty/main amd64 Packages 100 /var/lib/dpkg/status 5.2.1-3ubuntu15.1 0 500 http://gb.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages 5.2.1-3ubuntu15 0 500 http://gb.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
副作用
清除PPA会降低PPA安装的软件包的级别。 如果无法降级，因为此PPA中仅存在包，则将删除该包。 删除后，程序包的配置文件仍存在于系统中。