Did you configure ROOT 6.06/06 using “proper” flags for Ubuntu 16.04 with gcc 5.x? cmake -DCMAKE_CXX_FLAGS="-D_GLIBCXX_USE_CXX11_ABI=0" -Dcxx14="ON" -Dall="ON" -Ddavix="OFF" -Dr="OFF" -Dpythia8="OFF" -Dgeocad="ON" -Dbuiltin_ftgl="OFF" -Dbuiltin_glew="OFF" -Dsoversion="ON" ...Another...Flags...You...May...Need... In particular, for the time being, -DCMAKE_CXX_FLAGS="-D_GLIBCXX_USE_CXX11_ABI=0" is mandatory for ROOT 6.06/06 with gcc 5.x.