I recently was trying to `cabal install` (with a sandbox) a package I'd made, which depends on scotty-0.5.0. Cabal-install was giving me this message: $ cabal install Resolving dependencies... cabal: Could not resolve dependencies: trying: multicopter-0.0.1 (user goal) next goal: scotty (dependency of multicopter-0.0.1) rejecting: scotty-0.4.6, 0.4.5, 0.4.4, 0.4.3, 0.4.2, 0.4.1, 0.4.0, 0.3.0, 0.2.0, 0.1.0, 0.0.1 (conflict: multicopter => scotty>=0.5.0) Dependency tree exhaustively searched. Note: when using a sandbox, all packages are required to have consistent dependencies. Try reinstalling/unregistering the offending packages or recreating the sandbox. My first assumption was that scotty, and some other package that my package depend on, both want different versions of a third package. I tried removing everything else from the build-depends field, but I got the same message. Then I did a `cabal update` which appears to have fixed it. My question is: Should cabal-install, in this situation, say something like "I'm not aware of a version 0.5.0 for the 'scotty' package. Try `cabal update`" instead?