Sui mainnet is back online and transactions are flowing normally.
The end of epoch halt was triggered during the rollout of yesterday's long-term fix. As validators restarted to deploy the new binary, the randomness initialization that runs at the start of each epoch was unable to complete because it has a higher quorum threshold than Sui consensus. A latent bug in how that failure state is preserved across validator restarts then prevented the network from completing its transition to the next epoch.
Validators have implemented a fix that addresses both the underlying bug and the affected epoch, and network activity has resumed.
A more detailed incident review is forthcoming.