Resolving dependencies... cabal: Could not resolve dependencies: [__0] trying: liquid-parallel-3.2.2.0 (user goal) [__1] trying: parallel-3.2.2.0 (dependency of liquid-parallel) [__2] trying: base-4.12.0.0/installed-4.12.0.0 (dependency of parallel) [__3] next goal: liquid-base (dependency of liquid-parallel) [__3] rejecting: liquid-base-4.14.0.0 (conflict: base==4.12.0.0/installed-4.12.0.0, liquid-base => base==4.14.0.0) [__3] fail (backjumping, conflict set: base, liquid-base, liquid-parallel) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: base, liquid-parallel, liquid-base, parallel Try running with --minimize-conflict-set to improve the error message.