Does GSN require constantinople hardfork?

That is correct, RelayHub was compiled with solc 0.5.10. The default EVM target has been Petersburg (Constantinople) since solc 0.5.5, so it is possible that new opcodes were used in the bytecode, as you seem to have encountered.

How are you deploying RelayHub on your network? You should use the OpenZeppelin GSN Helpers, which will deploy RelayHub at the canonical address.

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