> ## Documentation Index
> Fetch the complete documentation index at: https://docs.celo.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Jello Upgrade

## Overview

The Jello upgrade for the Celo network enables OP Succinct Lite, a production-ready, zero-knowledge-powered fault proof system built in collaboration with OP Labs and Succinct.

## Specifications

### L1 Contract changes

The Jello upgrade included L1 contract changes. They have been been accepted by governance in [CGP-265](https://mondo.celo.org/governance/265) and executed by the Celo Security Council.

### Execution Layer changes

There's no execution layer changes in the Jello upgrade.

## Upgrade Timelines

The Jello upgrade activated on Mainnet and Celo Sepolia, with the activation process for each network occurring independently.

| Network      | Date & Time (UTC)         | Upgrade transaction                                                                                                                                                              |
| ------------ | ------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Celo Sepolia | Wed, Nov 05 2025 11:16:00 | [`0x736deb757f4708eeafecc961f36e14f3711c1d9f944e45c933b666329743b31a`](https://eth-sepolia.blockscout.com/tx/0x736deb757f4708eeafecc961f36e14f3711c1d9f944e45c933b666329743b31a) |
| Mainnet      | Wed, Dec 10 2025 10:24:22 | [`0x5fb3f2225dd2ba91efe941d4c9151df120ab06f6611b7b494bdecc96ff84c44b`](https://eth.blockscout.com/tx/0x5fb3f2225dd2ba91efe941d4c9151df120ab06f6611b7b494bdecc96ff84c44b)         |