Public bug reported: Installing the package "haskell-stack" and then trying to run the ghci interpreter results in
❯ stack ghci Writing implicit global project config file to: /home/janne/.stack/global-project/stack.yaml Note: You can change the snapshot via the resolver field there. Using latest snapshot resolver: lts-12.5 Downloaded lts-12.5 build plan. AesonException "Error in $.packages.cassava.constraints.flags['bytestring--lt-0_10_4']: Invalid flag name: \"bytestring--lt-0_10_4\"" Per https://github.com/commercialhaskell/stackage/issues/2759 and https://github.com/commercialhaskell/stack/issues/3345 this is apparently a bug in stack which has subsequently been fixed. Indeed downloading and installing the latest stack per the instructions at https://docs.haskellstack.org/en/stable/README/ works. More info as requested in bug reporting guidelines: 1) ❯ lsb_release -rd Description: Ubuntu 18.04.1 LTS Release: 18.04 2) haskell-stack version 1.5.1-1 ** Affects: haskell-stack (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1786197 Title: stack 1.5.1 broken on 18.04 (AesonException) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/haskell-stack/+bug/1786197/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs