Resolving dependencies... cabal: Could not resolve dependencies: [__0] trying: neuron-1.0.0.0 (user goal) [__1] trying: reflex-dom-core-0.6.0.0 (dependency of neuron) [__2] trying: reflex-0.7.1.0 (dependency of neuron) [__3] next goal: dependent-sum (dependency of neuron) [__3] rejecting: dependent-sum-0.7.1.0 (conflict: reflex-dom-core => dependent-sum>=0.6 && <0.7) [__3] skipping: dependent-sum-0.7.0.0 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=0.6 && <0.7' from 'reflex-dom-core') [__3] rejecting: dependent-sum-0.6.2.0 (conflict: neuron => dependent-sum>=0.7) [__3] skipping: dependent-sum-0.5, dependent-sum-0.4, dependent-sum-0.3.2.2, dependent-sum-0.3.2.1, dependent-sum-0.3.2.0, dependent-sum-0.3.1.0, dependent-sum-0.2.1.0, dependent-sum-0.2.0.2, dependent-sum-0.2.0.1, dependent-sum-0.2, dependent-sum-0.1, dependent-sum-0.6.2.2, dependent-sum-0.6.1, dependent-sum-0.6 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=0.7' from 'neuron') [__3] fail (backjumping, conflict set: dependent-sum, neuron, reflex-dom-core) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: neuron, reflex, reflex-dom-core, base, dependent-sum Try running with --minimize-conflict-set to improve the error message.