package fp-compiler-3.0.0 (not installed) failed to install/upgrade: trying to overwrite '/usr/lib/fpc/3.0.0/ppcx64', which is also in package fpc 3.0.0

[Nuno]

Following the normal apt upgrade, probably broken package.

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: fp-compiler-3.0.0 (not installed)
ProcVersionSignature: Ubuntu 4.4.0-36.55-generic 4.4.16
Uname: Linux 4.4.0-36-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
Date: Wed Sep 7 23:11:50 2016
DuplicateSignature:
 package:fp-compiler-3.0.0:(not installed)
 Unpacking fp-units-rtl-3.0.0 (3.0.0+dfsg-2) ...
 dpkg: error processing archive /var/cache/apt/archives/fp-units-rtl-3.0.0_3.0.0+dfsg-2_amd64.deb (--unpack):
  trying to overwrite '/usr/lib/fpc/3.0.0/units/x86_64-linux/rtl/cp1252.ppu', which is also in package fpc 3.0.0
ErrorMessage: trying to overwrite '/usr/lib/fpc/3.0.0/ppcx64', which is also in package fpc 3.0.0
InstallationDate: Installed on 2016-07-25 (44 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.1
 apt 1.2.12~ubuntu16.04.1
SourcePackage: fpc
Title: package fp-compiler-3.0.0 (not installed) failed to install/upgrade: trying to overwrite '/usr/lib/fpc/3.0.0/ppcx64', which is also in package fpc 3.0.0
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Paul Gevers (paul-climbing)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1568072, so it is being marked as such. The issue you are encountering is that you installed the fpc package from upstream (probably when you were installing the lazarus package). The lazarus team is not making fpc packages that are fully compatible with how things are done in Debian/Ubuntu. That is not something that is desirable to fixe on our side. However, we normally work around that issue, but that work around was temporarily missed, so the package that finally went into Xenial doesn't have it.

You can easily fix the issue on your system by running
apt-get remove fpc
apt-get install fpc