I use Ubuntu 15.10 64-bit. When I run
sudo apt-get install libpng-dev
the console prints
Reading package lists... Done Building dependency tree Reading state information... Done Note, selecting 'libpng12-dev' instead of 'libpng-dev' 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: libpng12-dev : Depends: libpng12-0 (= 1.2.51-0ubuntu3) but 1.2.51-0ubuntu18.104.22.168 is to be installed E: Unable to correct problems, you have held broken packages.
At first I tried installing libpng-dev in the Software Center, but it crashed when it tried installing libpng-dev. Then I googled, tried
sudo apt-get update sudo apt-get upgrade sudo apt-get install -f libpng-dev
but this didn't help. Maybe I should just reinstall Ubuntu? I'd have no problem with that, would just take me about an hour.
$ apt-cache policy libpng12-dev
libpng12-dev: Installed: (none) Candidate: 1.2.51-0ubuntu3 Version table: 1.2.51-0ubuntu3 0 500 http://de.archive.ubuntu.com/ubuntu/ wily/main amd64 Packages
$ apt-cache policy libpng12-0
libpng12-0: Installed: 1.2.51-0ubuntu22.214.171.124 Candidate: 1.2.51-0ubuntu126.96.36.199 Version table: *** 1.2.51-0ubuntu188.8.131.52 0 100 /var/lib/dpkg/status 1.2.51-0ubuntu3 0 500 http://de.archive.ubuntu.com/ubuntu/ wily/main amd64 Packages