Resolving dependencies... Error: cabal: Could not resolve dependencies: [__0] trying: mohws-0.2.1.9 (user goal) [__1] trying: network-bsd-2.8.1.0 (dependency of mohws) [__2] next goal: network (dependency of mohws) [__2] rejecting: network-3.1.2.7 (conflict: mohws => network>=2.6 && <3.0) [__2] skipping: network-3.1.2.5, network-3.1.2.2, network-3.1.2.1, network-3.1.2.0, network-3.1.0.1, network-3.1.0.0, network-3.0.1.1, network-3.0.1.0, network-3.0.0.1, network-3.0.0.0 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=2.6 && <3.0' from 'mohws') [__2] rejecting: network-2.8.0.1 (conflict: network-bsd => network>=3.0.0.0 && <3.0.2 || >=3.1.0.0 && <3.2) [__2] skipping: network-2.8.0.0, network-2.7.0.2, network-2.7.0.1, network-2.7.0.0, network-2.6.3.6, network-2.6.3.5, network-2.6.3.3, network-2.6.3.2, network-2.6.3.1, network-2.6.3.0, network-2.6.2.1, network-2.6.2.0, network-2.6.1.0, network-2.6.0.2, network-2.6.0.1, network-2.6.0.0, network-2.5.0.0, network-2.4.2.3, network-2.4.2.0, network-2.4.1.2, network-2.4.1.1, network-2.4.1.0, network-2.4.0.1, network-2.4.0.0, network-2.3.2.1, network-2.3.2.0, network-2.3.1.1, network-2.3.1.0, network-2.3.0.14, network-2.3.0.13, network-2.3.0.12, network-2.3.0.11, network-2.3.0.10, network-2.3.0.9, network-2.3.0.8, network-2.3.0.7, network-2.3.0.6, network-2.3.0.5, network-2.3.0.4, network-2.3.0.3, network-2.3.0.2, network-2.3.0.1, network-2.3, network-2.2.3.1, network-2.2.3, network-2.2.1.10, network-2.2.1.9, network-2.2.1.8, network-2.2.1.7, network-2.2.1.6, network-2.2.1.5, network-2.2.1.4, network-2.2.1.3, network-2.2.1.2, network-2.2.1.1, network-2.2.1, network-2.2.0.1, network-2.2.0.0, network-2.1.0.0, network-2.0 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=3.0.0.0 && <3.0.2 || >=3.1.0.0 && <3.2' from 'network-bsd') [__2] rejecting: network-3.1.2.6 (conflict: mohws => network>=2.6 && <3.0) [__2] skipping: network-3.1.2.4, network-3.1.2.3, network-3.1.1.1, network-3.1.1.0 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=2.6 && <3.0' from 'mohws') [__2] rejecting: network-2.6.3.4 (conflict: network-bsd => network>=3.0.0.0 && <3.0.2 || >=3.1.0.0 && <3.2) [__2] skipping: network-2.4.2.2, network-2.4.2.1 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=3.0.0.0 && <3.0.2 || >=3.1.0.0 && <3.2' from 'network-bsd') [__2] fail (backjumping, conflict set: mohws, network, network-bsd) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: network, mohws, network-bsd, bytestring, base Try running with --minimize-conflict-set to improve the error message.