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.

1. Initial Failure

   The transaction fails on mainnet with a generic HostError(Value, InvalidInput).

2. Run Decode

   Run grat decode <hash>. Grat identifies that the InvalidInput happened inside the Token contract during a transfer call.

3. Esclate to Trace

   Run grat trace <hash>. The hierarchical timeline shows that the swap contract passed a negative amount to the token contract.

4. 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.