TechFlow news: Aptos released a report on yesterday's mainnet incident, stating that the Aptos network began experiencing transaction delays around 16:15 PDT on October 18 (07:15 Beijing Time on October 19). The issue was not due to transaction load; submitted transactions were not lost, and no fork occurred. The problem stemmed from non-deterministic code, and a fix has now been deployed. The issue was resolved around 12:30 Beijing Time on October 19.
The root cause traces back to a change in the Aptos core codebase on August 22, 2023, and the launch of a fee schedule update on October 16, 2023—introducing more granular transaction fee/refund calculations. The initial code change introduced non-determinism only revealed by the FeeStatement. Specifically, validators agreed that a transaction’s gas budget was insufficient for execution, but due to the non-determinism introduced in the August code change, they could not agree on the exact amount of gas consumed up to that point. The team identified the issue and reverted the August code change, resolving the problem. Validator operators quickly deployed the corrected software. This marks the first significant on-chain delay experienced by the Aptos network since mainnet launch, and this particular non-deterministic scenario had not manifested in any test environments, including testnets.
