package qml-module-org-kde-activities (not installed) failed to install/upgrade: trying to overwrite '/usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/activities/libkactivitiesextensionplugin.so', which is also in package qml-module-org-kde-extensionplugin:amd64 5.21.0+p16.04+git20160430.0813-0

[iniz]

happened after i uninstalled kde plasma

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: qml-module-org-kde-activities (not installed)
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
Date: Mon May 2 14:32:59 2016
DuplicateSignature:
 Unpacking qml-module-org-kde-activities:amd64 (5.18.0-0ubuntu1) over (5.21.0+p16.04+git20160430.0813-0) ...
 dpkg: error processing archive /var/cache/apt/archives/qml-module-org-kde-activities_5.18.0-0ubuntu1_amd64.deb (--unpack):
  trying to overwrite '/usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/activities/libkactivitiesextensionplugin.so', which is also in package qml-module-org-kde-extensionplugin:amd64 5.21.0+p16.04+git20160430.0813-0
ErrorMessage: trying to overwrite '/usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/activities/libkactivitiesextensionplugin.so', which is also in package qml-module-org-kde-extensionplugin:amd64 5.21.0+p16.04+git20160430.0813-0
InstallationDate: Installed on 2016-04-30 (1 days ago)
InstallationMedia: budgie-remix 16.04 - Release amd64
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1
 apt 1.2.10ubuntu1
SourcePackage: kactivities-kf5
Title: package qml-module-org-kde-activities (not installed) failed to install/upgrade: trying to overwrite '/usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/activities/libkactivitiesextensionplugin.so', which is also in package qml-module-org-kde-extensionplugin:amd64 5.21.0+p16.04+git20160430.0813-0
UpgradeStatus: No upgrade log present (probably fresh install)

[Scarlett Gately Moore (scarlettmoore)]

Unpacking qml-module-org-kde-activities:amd64 (5.18.0-0ubuntu1) over (5.21.0+p16.04+git20160430.0813-0) ...
 dpkg: error processing archive /var/cache/apt/archives/qml-module-org-kde-activities_5.18.0-0ubuntu1_amd64.deb (--unpack):
  trying to overwrite '/usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/activities/libkactivitiesextensionplugin.so', which is also in package qml-module-org-kde-extensionplugin:amd64 5.21.0+p16.04+git20160430.0813-0

Tells me you are trying to install version 5.18.0 over 5.21.0 from where did you get 5.21.0+p16.04+git20160430.0813?

Anyway, you cannot do it this way, you must purge whatever PPA you got 5.21.0 from.