# Common Mistakes

## Common Pitfalls in Solver Operation Generation

### Solver Operation Configuration Issues

#### 1. Incorrect Solver Calldata Encoding

* ❌ Encoding the Atlas solver call interface instead of the internal solver contract call
* ✅ Should use: `solverContract.interface.encodeFunctionData('solve')`
* Common error: Using Atlas ABI to encode the call instead of the solver contract's ABI

#### 2. Outdated Contract Addresses

* Dapp Control address not matching the deployed network version
* Dapp signer address not matching the current environment
* Atlas contract address mismatch between environments

{% content-ref url="/spaces/cdwawPu1WZY0iOUAGHRD/pages/H86JMGHkLhsAtQ002bMv" %}
[Addresses & Endpoints](/polygon-fastlane/searcher-guides/addresses-and-endpoints.md)
{% endcontent-ref %}

#### 3. Gas Configuration

* Not accounting for gas overhead in the operation
* Using incorrect gas price calculations for legacy vs EIP-1559 transactions
* Not properly handling maxFeePerGas and maxPriorityFeePerGas for EIP-1559 transactions

#### 4. Signature Related Issues

* Using wrong signer for operation signing
* Not handling signature recovery parameters correctly
* Missing or incorrect chainId in signing process

#### 5. Deadline Configuration

* Setting too short or too long deadlines (deadline in block number)
* Using timestamps instead of block number for deadlines

#### 6. Bid Token Configuration

* Using incorrect token decimals in bid amounts
* Incorrect zero address usage for native token bids

#### 7. Operation Hash Calculation

* Incorrect user operation hash calculation for backrun transactions
* Not properly handling legacy vs EIP-1559 transaction parameters in hash calculation
* not using the opportunity transaction matching gas settings

#### 8. Permission and Access Issues

* Solver contract not properly authorized on Atlas

#### 9. Value Transfer Issues

* Incorrect handling of value field for native token transfers
* Not accounting for bid amount in value field when required
* Not sending the bidAmount to the executionEnvironment

#### 10. Environment Specific Issues

* Using production addresses in testing environment
* Not properly handling different network configurations
* Missing environment-specific parameter adjustments


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