Resolving dependencies... cabal: Could not resolve dependencies: [__0] trying: ghc-api-compat-8.10.7 (user goal) [__1] next goal: ghc (dependency of ghc-api-compat) [__1] rejecting: ghc-8.10.2/installed-8.10.2 (conflict: ghc-api-compat => ghc==8.10.5 || ==8.10.6 || ==8.10.7) [__1] skipping: ghc-8.10.2, ghc-8.10.1, ghc-8.8.3, ghc-8.8.1, ghc-8.6.5, ghc-8.6.4, ghc-8.6.1, ghc-8.4.4, ghc-8.4.3, ghc-8.4.1, ghc-8.2.2, ghc-8.2.1 (has the same characteristics that caused the previous version to fail: excluded by constraint '==8.10.5 || ==8.10.6 || ==8.10.7' from 'ghc-api-compat') [__1] fail (backjumping, conflict set: ghc, ghc-api-compat) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: ghc-api-compat, ghc