I am wondering if it is possible to set a value to an arbitrary storage key at genesis.

Let's say I want to populate the key 0x3fba98689ebed1138735e0e7a5a790abee99a84ccbfb4b82e714617e5e06f6f7 at genesis, but this key is not part of any GenesisConfig of any pallet I have installed in my runtime.

Is there a way to work around this ?

  • The key I have chosen for the question is not the concrete key I am trying to mutate, is just an example. Sep 28, 2022 at 9:04
  • I think you can edit the genesis spec file. What is your use-case? When do you need the insertion to happen? Sep 28, 2022 at 9:08
  • Indeed, editing the spec file was my first idea. Sep 29, 2022 at 9:19

1 Answer 1


Just insert the key/value into chain_spec["genesis"]["raw"]["top"].

This is what Subalfred does to fork off the chain https://github.com/hack-ink/subalfred/blob/3994cfe31dd13d3aaf757503da3e73afd186c319/src/subalfred/core/state/fork_off.rs#L142.


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