> ## Documentation Index
> Fetch the complete documentation index at: https://prism-ddf93e61.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Debugging Transactions

> A real-world walkthrough of fixing a Soroban error.

In this guide, we walk through the process of debugging a failed cross-contract swap.

<Steps>
  <Step title="Initial Failure">
    The transaction fails on mainnet with a generic `HostError(Value, InvalidInput)`.
  </Step>

  <Step title="Run Decode">
    Run `prism decode <hash>`. Prism identifies that the `InvalidInput` happened inside the `Token` contract during a transfer call.
  </Step>

  <Step title="Esclate to Trace">
    Run `prism trace <hash>`. The hierarchical timeline shows that the `swap` contract passed a negative amount to the `token` contract.
  </Step>

  <Step title="Root Cause Found">
    The root cause is a slippage calculation bug in the `swap` contract that resulted in a negative value under extreme market conditions.
  </Step>
</Steps>