Hello, Just merged is a new linter which checks the consistency of notes. In particular it checks that all note references reference an existing Note. The linter is integrated into the testsuite so you can run the linter (without building GHC) by saying ./hadrian/build test --only=notes and can accept the new output of the linter by saying ./hadrian/build test --only=notes --test-accept But you should probably not need to do this and instead fix your note references! Any issues please open a ticket. Cheers, Matt