Resolving dependencies... cabal: Could not resolve dependencies: [__0] trying: reflex-backend-socket-0.2.0.1 (user goal) [__1] trying: witherable-0.4.2 (dependency of reflex-backend-socket) [__2] next goal: reflex (dependency of reflex-backend-socket) [__2] rejecting: reflex-0.8.2.0 (conflict: witherable==0.4.2, reflex => witherable>=0.3 && <0.4) [__2] skipping: reflex-0.8.1.1, reflex-0.8.1.0, reflex-0.8.0.0, reflex-0.7.1.1, reflex-0.7.1.0, reflex-0.7.0.0, reflex-0.6.4.1, reflex-0.6.4, reflex-0.6.3, reflex-0.6.2.4, reflex-0.6.1, reflex-0.6 (has the same characteristics that caused the previous version to fail: excludes 'witherable' version 0.4.2) [__2] rejecting: reflex-0.5.0.1 (conflict: reflex-backend-socket => reflex>=0.7.1.0 && <0.9) [__2] skipping: reflex-0.5, reflex-0.4.0.1, reflex-0.4.0, reflex-0.3.2, reflex-0.3.1, reflex-0.3, reflex-0.2, reflex-0.1.1, reflex-0.1.0, reflex-0.0.1 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=0.7.1.0 && <0.9' from 'reflex-backend-socket') [__2] rejecting: reflex-0.7.2.0 (conflict: witherable==0.4.2, reflex => witherable>=0.3 && <0.4) [__2] skipping: reflex-0.6.2.3, reflex-0.6.2.1 (has the same characteristics that caused the previous version to fail: excludes 'witherable' version 0.4.2) [__2] fail (backjumping, conflict set: reflex, reflex-backend-socket, witherable) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: reflex-backend-socket, witherable, base, reflex Try running with --minimize-conflict-set to improve the error message.