Resolving dependencies... Configuring darcs-2.3.0... Failed to install darcs-2.3.0 Build log ( /home/builder/.cabal/logs/darcs-2.3.0.log ): cabal: Entering directory '/tmp/cabal-tmp-17127/darcs-2.3.0' cabal: Leaving directory '/tmp/cabal-tmp-17127/darcs-2.3.0' cabal: Error: some packages failed to install: darcs-2.3.0 failed during the configure step. The exception was: user error ('/opt/ghc/8.0.2/bin/ghc' exited with an error: /tmp/cabal-tmp-17127/darcs-2.3.0/Distribution/ShellHarness.hs:19:1: error: Failed to load interface for ‘Control.OldException’ Perhaps you meant Control.Exception (from base-4.9.0.0) Use -v to see a list of the files searched for. )