# Base Schedules Nov. 5 Denim Upgrade for Five Canonical Blocks Per Second By Simon Yoon Canonical URL: https://www.tokenpost.com/news/technology/46905 Published: 2026-11-02T20:51:39.000Z Updated: 2026-11-02T20:51:39.000Z Section: Technology > The upgrade is scheduled for 1 p.m. to 3 p.m. ET (18:00 to 20:00 UTC), and Base expects the network to remain operational. Node operators must upgrade to `base/base` v1.5.1 before activation. Base has set its Denim mainnet upgrade for Nov. 5, moving the network to five complete canonical blocks per second and changing how affected apps receive updates. The upgrade window is scheduled to run from 1 p.m. ET (18:00 UTC) to 3 p.m. ET (20:00 UTC) Thursday. Base expects the network to remain operational. Mainnet node operators must upgrade to base/base v1.5.1 before activation. Denim will replace the current cadence of one canonical block every two seconds with five complete blocks each second. Every block will have its own number, hash, state root and receipts. Flashblocks currently provide interim updates before a block becomes canonical; subscriptions to Flashblocks and pending-state access will end when the upgrade activates. Apps relying on Flashblocks subscriptions will need to migrate to canonical subscriptions, including newHeads and logs. Pending state will have no direct equivalent after Denim, so integrations that use it will need to move to the available canonical feeds. Operators upgrading from an older release must remove --enable-experimental-validity-transactions from the base-reth-node command if the flag is present. Leaving it in place will prevent the node from starting. Application code that uses block counts to measure time also needs review. Because block.number will advance 10 times faster in elapsed time, a duration defined by a fixed number of blocks will finish in one-tenth the time. block.timestamp will remain seconds-based, so its rate will not change with the faster block numbering. Fixed block-count settings in immutable or non-upgradeable code cannot be adjusted after deployment. Denim will also add BaseTime sub-second data. RPC responses will support optional millisecond fields such as timestampMs and blockTimestampMs, alongside timestamp fields expressed in seconds. Denim activated on Base Sepolia on Oct. 21 at 2 p.m. ET (18:00 UTC). The mainnet date adds a launch window to [the earlier plan for 200-millisecond blocks](). Mainnet activation is scheduled for Thursday, Nov. 5. ## Links in this article - [the earlier plan for 200-millisecond blocks](https://www.tokenpost.com/news/technology/39692)