AesonException Invalid flag name: \"bytestring--lt-0_10_4\""

[szymonlipinski]

I use stack from Ubuntu 18.04. I've got this error, and I found that I should run stack upgrade, so I run it.

λ ~/ stack --version
Version 1.5.1 x86_64
Compiled with:

and now I get:

λ ~/ stack ghc
Downloaded lts-11.13 build plan.    
AesonException "Error in $.packages.cassava.constraints.flags['bytestring--lt-0_10_4']: Invalid flag name: \"bytestring--lt-0_10_4\""

[mgsloan]

Hmm, so stack upgrade installed version 1.5.1? What does which stack say?

I'm guessing that maybe ~/.local/bin is not on your PATH, and so the newly installed version of stack isn't accessible from the commandline. So, perhaps add that to your PATH if it's not already there.

If that doesn't work, then perhaps try stack upgrade --binary-only or just use the install script:

curl -sSL https://get.haskellstack.org/ | sh

(see https://docs.haskellstack.org/en/stable/README/)

[szymonlipinski]

Version 1.7.1, Git revision 681c800873816c022739ca7ed14755e85a579565 (5807 commits) x86_64 hpack-0.28.2

λ ~/ which stack
/home/szymon/.local/bin/stack

λ ~/ stack upgrade --binary-only
Current Stack version: 1.7.1, available download version: 1.7.1
Skipping binary upgrade, you are already running the most recent version

λ ~/ curl -sSL https://get.haskellstack.org/ | sh
Stack Version 1.7.1 already appears to be installed at:
  /home/szymon/.local/bin/stack
Use 'stack upgrade' or your OS's package manager to upgrade,
or pass '-f' to this script to over-write the existing binary, e.g.:
  curl -sSL https://get.haskellstack.org/ | sh -s - -f

[mgsloan]

With 1.7.1, you should no longer get the AesonException

[szymonlipinski]

I have uninstalled the system's haskell-stack and the one installed locally. I've run curl -sSL https://get.haskellstack.org/ | sh and now all is fine. Thank you.

[ursachec]

Thanks @szymonlipinski, your fix helped on Debian 9.6!