我知道這非常類似於這個問題和這個，但那裡的答案都不適合我。當嘗試安裝這些問題中提到的軟體包時，apt-get 會拋出以下錯誤訊息：
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.
當我嘗試安裝那裡提到的依賴項時，我發現越來越多的依賴項。當我選擇「修復損壞的套件」時，Synaptic 套件管理器會給予錯誤訊息。我怎樣才能解決這個問題？
預先感謝，如果您需要更多信息，請發表評論。
更新：運行apt-cache policy webapp-container unity-webapps-service得到以下結果：
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： 版本資訊：
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：嘗試unity-webapps-service使用 aptitude 而不是 apt-get 安裝時：
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： 的輸出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
的輸出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：輸出apt-cache policy libqt5qml5：
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
輸出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.
答案1
我會冒這個險並留下回應。
主要問題似乎是 PPA ppa:mscore-ubuntu/mscore-stable。使用此 PPA，您無法使用所需的版本libqt5qml5
因此，使用以下命令刪除 PPA。
sudo ppa-purge ppa:mscore-ubuntu/mscore-stable
在那之後
sudo apt-get install -f
最後
sudo apt-get install unity-webapps-service
哪裡有問題？
該命令apt-cache policy libqt5qml5返回以下內容。 PPA ppa:mscore-ubuntu/mscore-stable 安裝較新的版本 (5.3.0)，libqt5qml5
但qtdeclarative-abi-5-2-1需要確切的版本 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 會降級 PPA 安裝的軟體包。如果無法降級，因為軟體包僅存在於該 PPA 中，則該軟體包將被刪除。刪除後，該套件的設定檔仍然存在於您的系統中。