Hi, I am trying to install a cabal package in a fresh, clean sandbox, but cabal fails with: cabal: Could not resolve dependencies: Dependency tree exhaustively searched. I'm using $ cabal -V cabal-install version 1.20.0.1 using version 1.20.0.0 of the Cabal library $ ghc -V The Glorious Glasgow Haskell Compilation System, version 7.8.2 Even when I try -v3 I do not get much more information: $cabal install --only-dependencies -v3 Using a sandbox located at /home/bjp/projects/curry-frontend/.cabal-sandbox Searching for ghc in path. Found ghc at /home/bjp/.ghc-config/ghc/bin/ghc ("/home/bjp/.ghc-config/ghc/bin/ghc",["--numeric-version"]) /home/bjp/.ghc-config/ghc/bin/ghc is version 7.8.2 looking for tool ghc-pkg near compiler in /home/bjp/.ghc-config/ghc/bin found ghc-pkg in /home/bjp/.ghc-config/ghc/bin/ghc-pkg ("/home/bjp/.ghc-config/ghc/bin/ghc-pkg",["--version"]) /home/bjp/.ghc-config/ghc/bin/ghc-pkg is version 7.8.2 ("/home/bjp/.ghc-config/ghc/bin/ghc",["--supported-languages"]) ("/home/bjp/.ghc-config/ghc/bin/ghc",["--info"]) The package database already exists: /home/bjp/projects/curry-frontend/.cabal-sandbox/x86_64-linux-ghc-7.8.2-packages.conf.d Reading available packages... Reading available packages... Reading installed packages... ("/home/bjp/.ghc-config/ghc/bin/ghc-pkg",["dump","--package-db=/home/bjp/projects/curry-frontend/.cabal-sandbox/x86_64-linux-ghc-7.8.2-packages.conf.d","-v0"]) ("/home/bjp/.ghc-config/ghc/bin/ghc",["--print-libdir"]) Found no modified add-source deps. Reading installed packages... ("/home/bjp/.ghc-config/ghc/bin/ghc-pkg",["dump","--global","-v0"]) ("/home/bjp/.ghc-config/ghc/bin/ghc-pkg",["dump","--package-db=/home/bjp/projects/curry-frontend/.cabal-sandbox/x86_64-linux-ghc-7.8.2-packages.conf.d","-v0"]) ("/home/bjp/.ghc-config/ghc/bin/ghc",["--print-libdir"]) Reading available packages... Choosing modular solver. Resolving dependencies... [__0] trying: curry-frontend-0.3.10 (user goal) [__1] trying: base-4.7.0.0/installed-018... (dependency of curry-frontend-0.3.10) [__2] trying: rts-1.0/installedbuil... (dependency of base-4.7.0.0/installed-018...) [__3] trying: integer-gmp-0.5.1.0/installed-dc4... (dependency of base-4.7.0.0/installed-018...) [__4] trying: ghc-prim-0.3.1.0/installed-948... (dependency of base-4.7.0.0/installed-018...) [__5] trying: curry-frontend-0.3.10:+split-syb [__6] trying: syb-0.4.1 (dependency of curry-frontend-0.3.10) [__7] trying: syb-0.4.1:!test [__8] trying: transformers-0.3.0.0/installed-7df... (dependency of curry-frontend-0.3.10) [__9] trying: process-1.2.0.0/installed-eaf... (dependency of curry-frontend-0.3.10) [_10] trying: unix-2.7.0.1/installed-23f... (dependency of process-1.2.0.0/installed-eaf...) [_11] trying: time-1.4.2/installed-b47... (dependency of unix-2.7.0.1/installed-23f...) [_12] trying: old-locale-1.0.0.6/installed-be1... (dependency of time-1.4.2/installed-b47...) [_13] trying: bytestring-0.10.4.0/installed-7de... (dependency of unix-2.7.0.1/installed-23f...) [_14] trying: deepseq-1.3.0.2/installed-716... (dependency of process-1.2.0.0/installed-eaf...) [_15] trying: array-0.5.0.0/installed-9f2... (dependency of deepseq-1.3.0.2/installed-716...) [_16] trying: mtl-2.1.2/installed-d71... (dependency of curry-frontend-0.3.10) [_17] trying: either-4.1.2 (dependency of curry-frontend-0.3.10) [_18] trying: transformers-base-0.4.2 (dependency of either-4.1.2) [_19] trying: transformers-base-0.4.2:+orphaninstances [_20] trying: semigroupoids-4.0.2 (dependency of either-4.1.2) [_21] trying: distributive-0.4.4 (dependency of semigroupoids-4.0.2) [_22] trying: distributive-0.4.4:-lib-werror [_23] trying: distributive-0.4.4:!test [_24] trying: transformers-compat-0.3.2 (dependency of distributive-0.4.4) [_25] trying: transformers-compat-0.3.2:-transformers3 [__0] fail (backjumping, conflict set: ) cabal: Could not resolve dependencies: 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. Does anybody have an idea what the problem is? Best Regards, Björn