Resolving dependencies... cabal: Could not resolve dependencies: [__0] next goal: transformers-compat (user goal) [__0] rejecting: transformers-compat-0.6.6, transformers-compat-0.6.5, transformers-compat-0.6.4, transformers-compat-0.6.2, transformers-compat-0.6.1.6, transformers-compat-0.6.1.5 (constraint from user target requires ==0.6.1.4) [__0] trying: transformers-compat-0.6.1.4 [__1] trying: transformers-compat:-five [__2] trying: transformers-compat:+four [__3] next goal: transformers (dependency of transformers-compat +/-five +/-four +/-three +/-two) [__3] rejecting: transformers-0.5.6.2/installed-0.5.6.2, transformers-0.5.6.2, transformers-0.5.5.2, transformers-0.5.5.0, transformers-0.5.4.0 (conflict: transformers-compat -five +four => transformers>=0.4.1 && <0.5) [__3] rejecting: transformers-0.5.2.0, transformers-0.5.1.0, transformers-0.5.0.1, transformers-0.5.0.0 (conflict: transformers-compat -five +/-four +/-three +/-two => transformers>=0.2 && <0.4 || >=0.4.1 && <0.5 || >=0.5.3 && <0.6) [__3] trying: transformers-0.4.3.0 [__4] next goal: base (dependency of transformers-compat) [__4] rejecting: base-4.14.1.0/installed-4.14.1.0 (conflict: transformers => base>=2 && <4.9) [__4] skipping: base-4.15.0.0, base-4.14.1.0, base-4.14.0.0, base-4.13.0.0, base-4.12.0.0, base-4.11.1.0, base-4.11.0.0, base-4.10.1.0, base-4.10.0.0, base-4.9.1.0, base-4.9.0.0 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=2 && <4.9' from 'transformers') [__4] rejecting: base-4.8.2.0, base-4.8.1.0, base-4.8.0.0, base-4.7.0.2, base-4.7.0.1, base-4.7.0.0, base-4.6.0.1, base-4.6.0.0, base-4.5.1.0, base-4.5.0.0, base-4.4.1.0, base-4.4.0.0, base-4.3.1.0, base-4.3.0.0, base-4.2.0.2, base-4.2.0.1, base-4.2.0.0, base-4.1.0.0, base-4.0.0.0, base-3.0.3.2, base-3.0.3.1 (constraint from non-upgradeable package requires installed instance) [__4] fail (backjumping, conflict set: base, transformers, transformers-compat) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: transformers-compat, base, transformers, transformers-compat:five, transformers-compat:four Try running with --minimize-conflict-set to improve the error message.