> ## Documentation Index > Fetch the complete documentation index at: https://docs.optimism.io/llms.txt > Use this file to discover all available pages before exploring further. # Network upgrades > Learn more about OP Stack network activations. # Network upgrade overview This page provides hardfork activation timestamps and links to detailed specifications. The documentation outlines the hardfork release process. The network upgrade naming scheme after the Bedrock upgrade follows a geology theme based on the next letter in the English alphabet. ## Activations Network upgrades are activated by timestamps. Failing to upgrade your OP Stack software before the timestamp will cause a chain divergence and you will need to resync the chain. Optimistic activation times refer to times that are pending governance approval. | Upgrade | Governance Approval | [Mainnet Activations](https://github.com/ethereum-optimism/superchain-registry/blob/main/superchain/configs/mainnet/superchain.toml) | [Sepolia Activations](https://github.com/ethereum-optimism/superchain-registry/blob/main/superchain/configs/sepolia/superchain.toml) | | --------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------ | | [Jovian](https://specs.optimism.io/protocol/jovian/overview.html?utm_source=op-docs%5C\&utm_medium=docs) | [approved](https://vote.optimism.io/proposals/3118571676657709551286937570456546163542507117143005939043790253732885172699) | Tue Dec 2 16:00:01 UTC 2025 (`1764691201`) | Wed Nov 19 16:00:01 UTC 2025 (`1763568001`) | | [Isthmus](https://specs.optimism.io/protocol/isthmus/overview.html?utm_source=op-docs\&utm_medium=docs) | [approved](https://vote.optimism.io/proposals/8705916809146420472067303211131851783087744913535435360574720946039078686841) | Fri May 9 16:00:01 UTC 2025 (`1746806401`) | Thu Apr 17 16:00:00 UTC 2025 (`1744905600`) | | [Holocene](https://specs.optimism.io/protocol/holocene/overview.html?utm_source=op-docs\&utm_medium=docs) | [approved](https://vote.optimism.io/proposals/20127877429053636874064552098716749508236019236440427814457915785398876262515) | Thu Jan 9 18:00:01 UTC 2025 (`1736445601`) | Tue Nov 26 15:00:00 UTC 2024 (`1732633200`) | | [Granite](https://specs.optimism.io/protocol/granite/overview.html?utm_source=op-docs\&utm_medium=docs) | [approved](https://gov.optimism.io/t/upgrade-proposal-10-granite-network-upgrade/8733) | Wed Sep 11 16:00:01 UTC 2024 (`1726070401`) around block `125235812` | Mon Aug 12 16:00:00 UTC 2024 (`1723478400`) around block `15837930` | | [Fjord](https://specs.optimism.io/protocol/fjord/overview.html?utm_source=op-docs\&utm_medium=docs) | [approved](https://gov.optimism.io/t/upgrade-proposal-9-fjord-network-upgrade/8236) | Wed Jul 10 16:00:01 UTC 2024 (`1720627201`) around block `122514212` | Wed May 29 16:00:00 UTC 2024 (`1716998400`) around block `12597930` | | [Ecotone](https://specs.optimism.io/protocol/ecotone/overview.html?utm_source=op-docs\&utm_medium=docs) | [approved](https://gov.optimism.io/t/upgrade-proposal-5-ecotone-network-upgrade/7669) | Thu Mar 14 00:00:01 UTC 2024 (`1710374401`) around block `117387812` | Wed Feb 21 17:00:00 UTC 2024 (`1708534800`) around block `8366130` | | [Delta](https://specs.optimism.io/protocol/delta/overview.html?utm_source=op-docs\&utm_medium=docs) | [approved](https://gov.optimism.io/t/final-upgrade-proposal-3-delta-network-upgrade/7310) | Thu Feb 22 00:00:00 UTC 2024 (`1708560000`) around block `116480612` | Fri Dec 22 00:00:00 UTC 2023 (`1703203200`) around block `5700330` | | [Canyon](https://specs.optimism.io/protocol/canyon/overview.html?utm_source=op-docs\&utm_medium=docs) | [approved](https://gov.optimism.io/t/final-upgrade-proposal-2-canyon-network-upgrade/7088) | Thu Jan 11 17:00:01 UTC 2024 (`1704992401`) around block `114696812` | Tue Nov 14 17:00:00 UTC 2023 (`1699981200`) around block `4089330` | | Bedrock | [approved](https://gov.optimism.io/t/final-upgrade-1-bedrock-protocol-upgrade-v2/5548) | Tue Jun 06 2023 16:28:23 UTC (`1686079703`) at block `105235063` | N/A | ## Upgrade process Network upgrades follow this general process in which the features included in the upgrade are put into a release version cut from the `develop` branch and then the software is deployed on production networks. "Baking" on a network means the node software has been deployed and is live. Engineers take this time to observe the behavior of the software on production networks. Node Software Release Timeline * `Devnet Upgrade Notice Period` is for core developers to upgrade the node software on an internal devnet prior to the activation timestamp. * `Upgrade Activates on Devnet` * `Baking on Devnet` * `Testnet Upgrade Notice Period` is to allow testnet node operators to upgrade the node software on testnet prior to the activation timestamp. * `Upgrade Activates on Testnet` * `Baking on Testnet` * `Governance Voting Review Period` is when the Optimism Collective's governance system reviews proposals, including network upgrade proposals. * `Governance Voting Period` is when the Optimism Collective's governance system votes on proposals. * `Veto Period` is when the Citizens' House of the governance system can veto a protocol upgrade that has been approved by the Token House. * `Cut Mainnet Release` * `Mainnet Upgrade Notice Period` is to allow mainnet node operators to upgrade the node software on mainnet prior to the activation timestamp. * `Upgrade Activated`