When running cabal build or cabal repl in the core/week04 folder I get the following error message when building the playground-common- package:

src/Auth.hs:130:41: error:
    Not in scope: type constructor or class 'JWT.EncodeSigner'
    Module 'Web.JWT' does not export 'EncodeSigner'
130 |         { _configJWTSignature       :: !JWT.EncodeSigner
    |                                         ^^^^^^^^^^^^^^^^ 

I am in the correct branch in the plutus-apps repo as per the cabl.project file in code/week04. I've run cabal update and it was successful.

Does anyone have any ideas how to resolve this?

  • 1
    Do you run cabal from nix-shell? Feb 17, 2022 at 9:02
  • 1
    yes, I do. It appears the issue was that I ran nix-shell under an old commit (for week 3) and restarting the shell after the commit was changed allowed cabal build to run
    – wildcatmik
    Feb 17, 2022 at 21:02

1 Answer 1


Be sure to do a git pull for both 'plutus-master' and 'plutus-pioneer-program'. Then set the right git-checkout tag (of the week's cabal project file) Restart nix-shell so it builds the 'plutus-master', after that you can do the following to resolve missing dependencies in the 'week' folder:

  • cabal clean
  • cabal update
  • cabal build
  • cabal repl

This should work

  • 3
    Thanks, the key here for me was to restart the nix-shell. Once I did this everything flowed as expected.
    – wildcatmik
    Feb 18, 2022 at 11:09

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