Upgrade coming to Flow Epoch Smart contracts for security improvement

The Flow team has a tentative plan to upgrade the epoch smart contracts on mainnet on Januray 3rd. This is a security improvement upgrade so it will not break any smart contracts, node software, but may cause a minor change to event listeners. More details about the change below.

Expected dates to get the changes in effect is as follows:

  • CanaryNet: Thursday, December 14th
  • Testnet: Monday, December 18th

And assuming that the upgrades on the canary and testnet go well,

  • Mainnet: Wednesday, January 3rd

This will give us enough time to make sure the upgrades are functioning properly on non-mainnet networks.

The change to FlowEpoch contract that will be used for the upgrade can be found in this pull request . The changes are documented in the PR.

The change is backward compatible for the node software. However it may bring a change to EpochSetup event listeners as it updates the event field randomSource. The field becomes a hex string of exactly 32 characters, instead of a decimal string of up to 20 characters.

Note - We are open to changing the timeline if the community provides feedback on the suggested change.

If you have any questions regarding these changes, please ask in the PR comments, on Discord in the #protocol-builders channel, or reply here.


The contract is updated on Canary


There is a small bug fix to the locked tokens contract that I am going to include during this upgrade. The change is in this PR. It has already been done on testnet and will be done at the same time as these upgrades on testnet and mainnet


The contracts have been updated on testnet. I’m having some CI issues in the PR that I need to fix before merging though, but we should be good to upgrade on mainnet in Jan assuming everything goes fine on testnet


We’re gonna push back the mainnet uprade to Jan 10th


The contract has been upgraded on mainnet: Flow Diver: Flow Blockchain Explorer

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