> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cdp.coinbase.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Troubleshooting

This guide covers common issues when sending sponsored userOperations with CDP Paymaster and how to debug them.

<Tip>
  For a complete list of error codes and their meanings, see the [Errors](/paymaster/reference-troubleshooting/errors) page.
</Tip>

## Transaction Rejected by Policy

**Symptom:** Your userOperation is rejected before reaching the chain.

**Common causes:**

* Contract address not in your allowlist
* Function not allowlisted for the contract
* Per-user or global spend limits exceeded
* Sender address doesn't have required attestation

**Solution:** Check your [Paymaster Configuration](https://portal.cdp.coinbase.com/products/bundler-and-paymaster) in CDP Portal:

1. Verify the contract address is in your allowlist
2. Confirm the specific function you're calling is allowed
3. Review your spend limits in the Configuration tab

## Execution Reverted

**Symptom:** The userOperation made it onchain but the transaction reverted.

This means the smart contract execution failed. Common causes:

| Cause                      | Solution                                        |
| -------------------------- | ----------------------------------------------- |
| Insufficient gas           | Increase `callGasLimit` or `preVerificationGas` |
| Invalid callData           | Verify your encoded function call is correct    |
| Contract logic error       | Debug your contract with Tenderly               |
| Insufficient token balance | Ensure the account has required tokens          |

### Debugging with Tenderly

[Tenderly](https://dashboard.tenderly.co/) is useful for simulating and debugging userOperations.

**To debug gas issues:**

1. Go to Tenderly and select the Entrypoint contract: `0x5ff137d4b0fdcd49dca30c7cf57e578a026d2789`
2. Use the `simulateHandleOp` function
3. Paste your userOperation in the `op` field (wrap it in array brackets `[{...}]`)

<Frame>
  <img src="https://mintcdn.com/coinbase-prod/XD49nliTOz77YuSk/paymaster/images/pb-paymaster-tenderly-entrypoint.png?fit=max&auto=format&n=XD49nliTOz77YuSk&q=85&s=f92e0b97c76a8286953e49e91a280c54" alt="Tenderly Entrypoint simulation" width="1842" height="1702" data-path="paymaster/images/pb-paymaster-tenderly-entrypoint.png" />
</Frame>

**To debug contract logic:**

1. Enter your smart contract's address
2. Paste the `callData` from your userOperation
3. Run the simulation to see where it fails

<Frame>
  <img src="https://mintcdn.com/coinbase-prod/gFuoXXgHmk2Suwdi/paymaster/images/pb-paymaster-tenderly-dev-debug.png?fit=max&auto=format&n=gFuoXXgHmk2Suwdi&q=85&s=efe38a80affa69c9fac225f042632321" alt="Tenderly contract debugging" width="1220" height="1036" data-path="paymaster/images/pb-paymaster-tenderly-dev-debug.png" />
</Frame>

<Tip>
  Having your contract [verified on Basescan](https://book.getfoundry.sh/reference/forge/forge-verify-contract) makes debugging much easier.
</Tip>

### Decoding Revert Data

If you see an error like:

```json theme={null}
{
  "code": -32004,
  "message": "execution reverted with data",
  "data": "0xed6c3dec00000000000000000000000036e53f56454e1206f775dafe2b33c1b737c43632"
}
```

Use an [ABI decoder](https://bia.is/tools/abi-decoder/) to decode the error:

1. Upload your contract's ABI
2. Paste the `data` field
3. The decoder will show the specific error and parameters

## Invalid Chain ID

**Symptom:** Request rejected with chain ID mismatch error.

**Cause:** You're using a Paymaster URL for a different network than your transaction targets.

**Solution:** In [CDP Portal](https://portal.cdp.coinbase.com/products/bundler-and-paymaster), check the network dropdown in the top right corner and ensure it matches your transaction's chain:

* **Base Mainnet** — Chain ID `8453`
* **Base Sepolia** — Chain ID `84532`

<Frame>
  <img src="https://mintcdn.com/coinbase-prod/gFuoXXgHmk2Suwdi/paymaster/images/pb-paymaster-chainid.png?fit=max&auto=format&n=gFuoXXgHmk2Suwdi&q=85&s=370eec910336856e60fb9befea36b446" alt="Network selection in CDP Portal" width="1662" height="728" data-path="paymaster/images/pb-paymaster-chainid.png" />
</Frame>

## Invalid Signature

**Symptom:** Error message about account signature or paymaster signature check failing.

```
UserOperation rejected because account signature check failed 
(or paymaster signature, if the paymaster uses its data as signature).
```

**Cause:** The userOperation was modified after the Paymaster signed it.

The Paymaster signs the complete userOperation. If you change any field after calling `getPaymasterData()`, the signature becomes invalid.

**Solution:**

1. Finalize all userOperation fields (`callData`, gas limits, etc.) **before** requesting the Paymaster signature
2. Don't modify the userOperation after receiving `paymasterAndData`
3. If you need to change something, request a new Paymaster signature

<Warning>
  When batching multiple userOperations, ensure each one has its own matching Paymaster signature. Signatures are not interchangeable between operations.
</Warning>

## Sponsorship Not Applied

**Symptom:** Transaction goes through but user paid gas instead of sponsorship.

**Common causes:**

* Wallet doesn't support paymaster capabilities
* `paymasterService` capability not passed correctly
* Using an EOA instead of a smart account

**Solution:**

1. Verify you're using a smart account (check with `eth_getCode` — should return non-empty)
2. Confirm the wallet supports `paymasterService` capability
3. Check that you're passing the paymaster URL in the correct format for your SDK

## Still Stuck?

If you've tried the above and are still having issues:

1. **Check the Logs tab** in [CDP Portal](https://portal.cdp.coinbase.com/products/bundler-and-paymaster) for detailed request/response data
2. **Export your userOp logs** for offline analysis
3. **Reach out in [CDP Discord](https://discord.com/invite/cdp)** in the `#paymaster` channel — include your error message, userOperation details, and what you've tried