# Bundler Error Codes

Bundler error codes are the JSON-RPC error codes, standardized in EIP-7769, that an ERC-4337 bundler returns when it rejects a user operation, such as `-32500` when EntryPoint validation fails or `-32521` when execution reverts.

The bundler implements the [EIP-7769](https://eips.ethereum.org/EIPS/eip-7769) spec which standardizes ERC-4337 bundler error codes across different bundler implementations.

## EIP-7769 Error Codes

| Error Code | Description |
|------------|-------------|
| -32602 | Invalid UserOperation struct/fields |
| -32500 | Rejected by EntryPoint contract's simulateValidation |
| -32501 | Rejected by paymaster contract's validatePaymasterUserOp |
| -32502 | Violation of ERC-7562 opcode validation rules |
| -32503 | UserOperation out of time-range |
| -32504 | Paymaster throttled or banned by ERC-7562 reputation rules |
| -32505 | Paymaster stake or unstake-delay too low |
| -32507 | Wallet signature check failed |
| -32508 | Paymaster balance insufficient for pending UserOperations |
| -32521 | UserOperation execution reverted |

## Standard JSON-RPC Error Codes

| Error Code | Description |
|------------|-------------|
| -32603 | Internal error - indicates an internal failure in the bundler |