# AA23 reverted (or OOG)

`AA23 reverted (or OOG)` is an ERC-4337 EntryPoint error that means the smart account's `validateUserOp` function reverted or ran out of gas while validating the user operation.

:::info
OOG = Out Of Gas
:::

The `validateUserOp` function of the smart account either reverted or ran out of gas.

## Possible solutions

* Verify that the `verificationGasLimit` is high enough to cover the `validateUserOp` function's gas costs.
* Verify that the `validateUserOp` function is implemented with the correct logic, and that the user operation is supposed to be valid.
* Make sure the signature verification logic of the smart account is implemented correctly. Namely, correct implementations should **not** revert when the signature is invalid. If you are not looking to use neither time-based signatures nor a signature aggregator, you should simply return `uint(1)` for invalid signatures in the `validateUserOp` function.
* If all else fails, investigate why the `validateUserOp` function reverted using tools like [Tenderly](https://tenderly.co/).