Could not find a configuration file for package "ECM" that is compatible with requested version 1.5.0

Try to clone, compile and install the extra-cmake-modules KDE project. 

git clone [email protected]:frameworks/extra-cmake-modules.git
cd extra-cmake-modules
mkdir build && cd build    
cmake ..
make && sudo make install

In my case I simply had to install the extra-cmake-modules package.