The outage was the second major network disruption in 2025, with both incidents requiring a block reorganization that rolled back some activity.
The team behind Starknet, an Ethereum layer‑2 (L2) scaling network, released a post-mortem report outlining the root cause of the temporary mainnet downtime on Monday.
The root cause of the mainnet downtime was a discrepancy in the network state between the blockifier execution layer and the proving layer that checks that the execution layer is processing transactions correctly, according to the report. The Starknet team explained:
This incorrect execution never saw L1 finality thanks to Starknet’s proving layer,” the StarkNet team said, highlighting how the proving layer functioned properly by flagging the error and not committing the faulty transactions to the ledger.
