This upgrade marks a significant milestone in our ongoing efforts to enhance the performance and capabilities of the Flow blockchain. Crescendo enhances Flow’s scalability and decentralization at the protocol as well as upgrades the developers experience with Cadence 1.0 and full EVM equivalence, removing complexities and constraints for all builders.
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You can learn all about Crescendo here.

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Upgrade Date and Downtime

The Crescendo upgrade is scheduled to take place on August 14th, 8am PT. During this period, Flow’s Testnet will be in maintenance for approximately six hours. This means the testnet network will not process transactions or events. Updates will be shared via the Flow Status page and the Flow Discord. We understand the importance of testnet for developers, and the Flow Foundation team is working to minimize disruption.

To ensure a smooth transition for your contracts during the Crescendo upgrade, it is crucial that all contracts are staged before the upgrade. This preparation will facilitate a seamless migration, allowing you to experiment and explore the new features on Flow without any hitches. To learn more details on the process of staging your contracts, you can visit our Migration Hub for detailed guidelines, step-by-step instructions, and further information.

How to migrate your updated smart contract to Cadence 1.0?

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In order to migrate your updated smart contract to Cadence 1.0, it's crucial to stage it on the Testnet network. By staging your smart contract, the CLI tool will verify that the code is syntactically correct for the Cadence 1.0 upgrade, and will be migrated during the testnet Crescendo Network Upgrade. To do so, here’s the command:

flow-c1 migrate stage [YourContractName] --network=testnet

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Confirm the Contract is Staged​‍

To confirm that your contract is ready for migration and has been successfully staged, execute the following command:

flow-c1 migrate is-staged [YourContractName] --network=testnet

A response of “true” indicates that your contract has been approved by the Flow Blockchain Testnet network and is ready for the migration process.

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Validate your contract​

To validate your contract, execute the following command:

flow-c1 migrate is-validated [YourContractName] --network=testnet

A response of “true” indicates that your contract has been successfully staged and validated. Validation passes if the contract was successfully migrated over in the last emulated migration.

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You can view all currently staged contracts and see reports on migration status through the Migrations Data Repository.

Thank you for being an integral part of the Flow community, we look forward to seeing the exciting innovations that Crescendo will enable on Flow. Below you can find additional resources to help you with the migration process. Please reach out to us via our Discord if you have any issues or questions.

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Resources

Cadence 1.0 Breaking Changes - Learn about the changes coming to the language of Flow

Cadence 1.0 Migration Guide - Access in-depth information and tutorials on how to update your code for Cadence 1.0

Cadence Staging - A detailed walkthrough on how to Stage your contracts.

‍Flow Certified Developer Program - Find professional teams you can hire to help with the work for the Crescendo Upgrade.

For further support, you can join the Flow Discord and ask any questions or join our weekly Developer Office Hours (Thursday, 10am PT, every week).