Tx Doctor / EVM error library / Unknown custom error selector
EVM error: Unknown custom error selector
The revert data starts with a 4-byte selector that is not part of the ERC-20 / Panic standards. Custom errors are defined per contract, so the selector only means something in that contract's ABI.
Why it happens
- The contract uses Solidity custom errors (cheaper than strings) and did not publish them in the ABI you have.
- A proxy contract forwarded the revert from an implementation you are not looking at.
- The selector belongs to a library error (OpenZeppelin, Solmate) used internally.
How to fix it
- Look the selector up in the contract's verified ABI on the explorer or in openchain.xyz/signatures.
- Simulate the transaction with a tracer (Tenderly, Etherscan debugger) to see which sub-call reverted.
- Ask the protocol team — custom error names are documented in their repo.
What it looks like in the wallet or explorer
custom error 0x8c379a0… (selector not in the public signature database)
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