Because PPA's don't have an actual bug tracker and they're pretty badly maintained, I figure I would just ask how to fix this here.

The package libvlccore9 in the vlc-master PPA is trying to install /usr/lib/x86_64-linux-gnu/libvlccore.so.9.0.0 which is supposed to be installed by libvlccore8.

Reading package lists... Done

Building dependency tree       

Reading state information... Done

The following packages were automatically installed and are no longer required:

  libodbcinstq4-1 vlc-bin vlc-l10n vlc-plugin-notify vlc-plugin-qt vlc-plugin-samba vlc-plugin-skins2 vlc-plugin-video-splitter vlc-plugin-visualization

Use 'sudo apt autoremove' to remove them.

The following NEW packages will be installed:

  libvlccore9

0 upgraded, 1 newly installed, 0 to remove and 2 not upgraded.

34 not fully installed or removed.

Need to get 470 kB of archives.

After this operation, 1,243 kB of additional disk space will be used.

Get:1 http://ppa.launchpad.net/videolan/master-daily/ubuntu artful/main amd64 libvlccore9 amd64 3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1 [470 kB]

Fetched 470 kB in 1s (279 kB/s)      

(Reading database ... 322201 files and directories currently installed.)

Preparing to unpack .../libvlccore9_3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1_amd64.deb ...

Unpacking libvlccore9:amd64 (3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1) ...

dpkg: error processing archive /var/cache/apt/archives/libvlccore9_3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1_amd64.deb (--unpack):

 trying to overwrite '/usr/lib/x86_64-linux-gnu/libvlccore.so.9.0.0', which is also in package libvlccore8:amd64 3.0.0~~git20171208+r73126+99~ubuntu17.10.1

dpkg-deb: error: subprocess paste was killed by signal (Broken pipe)

Errors were encountered while processing:

 /var/cache/apt/archives/libvlccore9_3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1_amd64.deb

E: Sub-process /usr/bin/dpkg returned an error code (1)

question is why is that, libvlccore8 doesn't show that file,

apt-file show libvlccore8

libvlccore8: /usr/lib/x86_64-linux-gnu/libvlccore.so.8

libvlccore8: /usr/lib/x86_64-linux-gnu/libvlccore.so.8.0.0

libvlccore8: /usr/share/bug/libvlccore8/control

libvlccore8: /usr/share/bug/libvlccore8/presubj

libvlccore8: /usr/share/doc/libvlccore8/NEWS.Debian.gz

libvlccore8: /usr/share/doc/libvlccore8/changelog.Debian.gz

libvlccore8: /usr/share/doc/libvlccore8/copyright

I have a libvlccore8

dpkg -l | grep -i libvlccore

rc  libvlccore7                                   2.1.6-0ubuntu14.04.1                            amd64        base library for VLC and its modules

ii  libvlccore8:amd64                             3.0.0~~git20171208+r73126+99~ubuntu17.10.1      amd64        base library for VLC and its modules

But I can't even remove it in the current state,

sudo apt-get --purge remove libvlccore8

Reading package lists... Done

Building dependency tree       

Reading state information... Done

You might want to run 'apt --fix-broken install' to correct these.

The following packages have unmet dependencies:

 libvlc5 : Depends: libvlccore9 (>= 3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1~) but it is not going to be installed

 phonon4qt5-backend-vlc : Depends: libvlccore8 (>= 2.0.0) but it is not going to be installed

 vlc-plugin-base : Depends: libvlccore9 (>= 3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1~) but it is not going to be installed

                   Depends: vlc-plugin-abi-4-0-0

 vlc-plugin-notify : Depends: libvlccore9 (>= 3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1~) but it is not going to be installed

                     Depends: vlc-plugin-abi-4-0-0

 vlc-plugin-qt : Depends: libvlccore9 (>= 3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1~) but it is not going to be installed

                 Depends: vlc-plugin-abi-4-0-0

 vlc-plugin-samba : Depends: libvlccore9 (>= 3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1~) but it is not going to be installed

                    Depends: vlc-plugin-abi-4-0-0

 vlc-plugin-skins2 : Depends: libvlccore9 (>= 3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1~) but it is not going to be installed

                     Depends: vlc-plugin-abi-4-0-0

 vlc-plugin-video-output : Depends: libvlccore8 (= 3.0.0~~git20171208+r73126+99~ubuntu17.10.1) but it is not going to be installed

 vlc-plugin-video-splitter : Depends: libvlccore9 (>= 3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1~) but it is not going to be installed

                             Depends: vlc-plugin-abi-4-0-0

 vlc-plugin-visualization : Depends: libvlccore9 (>= 3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1~) but it is not going to be installed

                            Depends: vlc-plugin-abi-4-0-0

E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).

And, i can't run --fix-broken install because then it tries to do the same thing that fails...

apt-get --fix-broken install

Reading package lists... Done

Building dependency tree       

Reading state information... Done

Correcting dependencies... Done

The following packages were automatically installed and are no longer required:

  libodbcinstq4-1 vlc-bin vlc-l10n vlc-plugin-notify vlc-plugin-qt vlc-plugin-samba vlc-plugin-skins2 vlc-plugin-video-splitter vlc-plugin-visualization

Use 'sudo apt autoremove' to remove them.

The following additional packages will be installed:

  libvlccore9

The following NEW packages will be installed:

  libvlccore9

0 upgraded, 1 newly installed, 0 to remove and 3 not upgraded.

34 not fully installed or removed.

Need to get 0 B/470 kB of archives.

After this operation, 1,243 kB of additional disk space will be used.

Do you want to continue? [Y/n] y

(Reading database ... 322201 files and directories currently installed.)

Preparing to unpack .../libvlccore9_3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1_amd64.deb ...

Unpacking libvlccore9:amd64 (3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1) ...

dpkg: error processing archive /var/cache/apt/archives/libvlccore9_3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1_amd64.deb (--unpack):

 trying to overwrite '/usr/lib/x86_64-linux-gnu/libvlccore.so.9.0.0', which is also in package libvlccore8:amd64 3.0.0~~git20171208+r73126+99~ubuntu17.10.1

dpkg-deb: error: subprocess paste was killed by signal (Broken pipe)

Errors were encountered while processing:

 /var/cache/apt/archives/libvlccore9_3.0.0~rc1~~git20171213+r73247+108~ubuntu17.10.1_amd64.deb

E: Sub-process /usr/bin/dpkg returned an error code (1)