# Runtime release notification for v1.5.0 \[01.05.2025\]

**URL:** <https://forum.polkadot.network/t/runtime-release-notification-for-v1-5-0-01-05-2025/12778>\
**Category:** Tech Talk\
**Tags:** runtime-releases\
**Created:** [May 1, 2025, 12:23pm UTC](https://forum.polkadot.network/t/runtime-release-notification-for-v1-5-0-01-05-2025/12778 "2025-05-01T12:23:30Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![anaelleltd](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.polkadot.network/anaelleltd/32/7664_2.png) [@anaelleltd](https://forum.polkadot.network/u/anaelleltd)\
**Post date:** [May 1, 2025, 12:23pm UTC](https://forum.polkadot.network/t/runtime-release-notification-for-v1-5-0-01-05-2025/12778/1 "2025-05-01T12:23:30Z")

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**Runtime release notification**

Hello,

This is to advise you that the Polkadot community is currently voting to upgrade the [_Kusama Relay chain_](https://kusama.subsquare.io/referenda/519) to the [v1.5.0 release](https://github.com/polkadot-fellows/runtimes/releases/tag/v1.5.0).

This is a major runtime upgrade that enables Elastic Scaling on Kusama, as part of a new [scalability model](https://www.parity.io/blog/polkadot-web3-cloud) described in depth [here](https://www.parity.io/blog/scalability-tradeoffs-polkadot-web3).

🚨 **Breaking change:** 🚨

This v1.5.0 release contains a change that adds an additional parameter to the `dry-run` functionality, which is a breaking change for the Runtime API. You can find more information about this change [here](https://github.com/polkadot-fellows/runtimes/pull/623/files#diff-75274b2ae3c60718590ca5aea28a21c0d4607f45df60573145545dbb9e4cb467R1183-R1184).

We recommend that all ecosystem builders that are calling the `DryRunApi` upgrade their code to handle the function signature.

🚧 **Important note for Ecosystem builders:** 🚧

The v1.5.0 release contains a change that enforces switching from [Version 1](https://github.com/paritytech/polkadot-sdk/blob/51e29401648c23aedeab8c4219d1051a772a1143/polkadot/primitives/src/v8/mod.rs#L514) to [Version 2](https://github.com/paritytech/polkadot-sdk/blob/51e29401648c23aedeab8c4219d1051a772a1143/polkadot/primitives/src/vstaging/mod.rs#L66) of the `CandidateDescriptor` primitive used by parachain consensus and exposed in the events `CandidateBacked` and `CandidateIncluded`.

Tooling and indexers that display this information must be updated to target the correct version of the primitive by following the instructions posted [here](https://github.com/polkadot-fellows/runtimes/issues/662#issuecomment-2841871647).

The projected enactment date for this runtime upgrade is 9th May 2025.

Many thanks.

---

<div class="post-metadata">

**Author:** ![anaelleltd](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.polkadot.network/anaelleltd/32/7664_2.png) [@anaelleltd](https://forum.polkadot.network/u/anaelleltd)\
**Post date:** [May 1, 2025, 12:24pm UTC](https://forum.polkadot.network/t/runtime-release-notification-for-v1-5-0-01-05-2025/12778/2 "2025-05-01T12:24:17Z")

</div>

**Runtime release notification**

Hello,

This is to advise you that the Polkadot community is currently voting to upgrade the [_Polkadot Relay chain_](https://polkadot.subsquare.io/referenda/1546) to the [v1.5.0 release](https://github.com/polkadot-fellows/runtimes/releases/tag/v1.5.0).

🚨 **Breaking change:** 🚨  
This v1.5.0 release contains a change that adds an additional parameter to the `dry-run` functionality, which is a breaking change for the Runtime API. You can find more information about this change [here](https://github.com/polkadot-fellows/runtimes/pull/623/files#diff-75274b2ae3c60718590ca5aea28a21c0d4607f45df60573145545dbb9e4cb467R1183-R1184).  
We recommend that all ecosystem builders that are calling the `DryRunApi` upgrade their code to handle the function signature.

🚧 **Important note for Ecosystem builders:** 🚧  
The v1.5.0 release contains a change in the `CandidateDescriptor` primitive used by parachain consensus and exposed in the events `CandidateBacked` and `CandidateIncluded`.Tooling and indexers that display this information must be updated to target the correct version of the primitive by following the instructions posted [here](https://github.com/polkadot-fellows/runtimes/issues/662#issuecomment-2841871647).

**Additional notes for Ecosystem builders:**  
A [Polkadot Technical Fellowship calendar](https://forum.polkadot.network/t/polkadot-technical-fellowship-calendar/11598) has been set up to log basic information about upcoming runtime releases and Technical Fellowship calls. You can subscribe to the Google calendar to access advance notices in real time.

The projected enactment date for this runtime upgrade is 14th May 2025.

Many thanks.