Why does my EIP-7702 UserOperation fail with an invalid fields error or AA10 on EntryPoint v0.7?

Last updated: August 13, 2026

If you're sending an EIP-7702-delegated UserOperation to Alchemy's Bundler API on EntryPoint v0.7 and set an eip7702Auth field, you may run into an error depending on how the factory field is set.

Symptom

  • Setting factory to the literal 0x7702 marker on eth_sendUserOperation or eth_estimateUserOperationGas returns -32602 invalid 1st argument: userOperation invalid user operation fields, because 0x7702 is not a valid 20-byte address.

  • Padding the marker out to a full 20-byte address (for example 0x7702000000000000000000000000000000000000) passes field validation, but the request then fails during simulation with AA10 sender already constructed.

Cause

ERC-7769 describes a convention where factory is set to a 0x7702 marker to indicate that a UserOperation is for an EIP-7702-delegated EOA. This marker is supported starting with EntryPoint v0.8. On EntryPoint v0.7, Alchemy's bundler does not recognize the 0x7702 marker convention, so the literal marker fails field validation because it isn't a valid 20-byte address. Padding it out to a valid address gets past that check, but the bundler then treats it as a normal account-factory deployment, which is not what's needed for a sender that's already authorized through EIP-7702 delegation.

Resolution

For EIP-7702-delegated senders on EntryPoint v0.7, omit both factory and factoryData and rely on eip7702Auth alone to carry the authorization. The factory and factoryData fields are only needed when the account isn't yet on-chain and needs to be deployed, which isn't the case for a delegated EOA.

If you're on EntryPoint v0.8, the 0x7702 factory marker is supported natively.

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