I followed Connect a local parachain tutorial and successfully run my local parachain node with this command:

./target/release/parachain-collator \
--alice \
--collator \
--force-authoring \
--chain rococo-local-parachain-2000-raw.json \
--base-path /tmp/parachain/alice \
--port 40333 \
--ws-port 8844 \
-- \
--execution wasm \
--chain <relay chain raw chain spec> \
--port 30343 \
--ws-port 9977

But while follow Connect to Rococo testnet tutorial, I don't know how to fill the <relay chain raw chain spec> field to start local parachain node. Do I need the chain specification file of Rococco testnet to run my local parachain node?

1 Answer 1


In order to connect your parachain to a relay chain you need its chain spec file.

In the tutorial, the relay chain you want to connect is rococo. The chain spec is public: https://github.com/paritytech/polkadot/blob/master/node/service/chain-specs/rococo.json

I suggest to download this file in your node and run the same command with:

--chain ./rococo.json \

You can see the spec files of other public networks: https://github.com/paritytech/polkadot/tree/master/node/service/chain-specs

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