USDC

EURC

<h2 id="tldr">TLDR</h2>
<ul>
 <li>Circle will start lowering burn limits on its legacy Cross-Chain Transfer Protocol (CCTP V1) on October 31, 2026.</li>
 <li>The old contracts are set to be paused on December 1, 2026, ending crosschain USDC transfers through V1.</li>
 <li>Apps still on V1 must move to CCTP V2, which uses different contracts and APIs and is not backward compatible.</li>
 <li>Circle says pending redemptions will stay available, with minting capacity kept in place to process them before the pause.</li>
 <li>CCTP V2 offers Standard and Fast Transfer modes, programmable hooks, and support for 27 blockchains.</li>
</ul>
Circle will begin winding down the legacy version of its Cross-Chain Transfer Protocol on October 31. The system, known as CCTP V1, moves the USDC stablecoin between blockchains.
Apps that still use it will face lower transfer limits through November. The old contracts are set to be paused on December 1, 2026.
<a href="https://www.circle.com/blog/migrate-to-cctp-v2-ahead-of-cctp-v1-legacy-deprecation" rel="noopener noreferrer nofollow">Circle first announced</a> the move away from V1 on November 14, 2025. It published the October to December timetable on August 27, 2026. The company says this gave the industry nearly a year of notice.
<h2 id="how-the-usdc-wind-down-works">How the USDC Wind-Down Works</h2>
CCTP moves USDC by burning it on one blockchain and minting it on another. A burn limit caps how much USDC can enter that process.
Starting October 31, Circle will reduce V1 burn limits. Performance will then decline gradually over about one month.
Circle’s migration guide says message limits will keep tightening until no new burns can begin. The goal is for transfer volume to reach zero before the contracts are fully paused.
Once the pause takes effect, any app still pointing to V1 will stop moving USDC across chains. Circle says migrating is required, not just recommended.
Pending redemptions will be handled differently. Circle says they will remain available during the phase-out.
The company plans to keep minting allowances above the total of pending attestations. An attestation is Circle’s signed approval for burned USDC to be minted on the destination chain. This is meant to let outstanding transfers finish before the full pause.
<h2 id="what-developers-need-to-change">What Developers Need to Change</h2>
CCTP V2, now simply called CCTP, uses separate contracts and APIs. Circle says it is not backward compatible with V1.
The guide lists new contracts, including TokenMessengerV2 and MessageTransmitterV2. The depositForBurn function now includes parameters for the allowed destination caller, maximum fee, and minimum finality threshold.
The attestation process also changes. Instead of pulling message bytes from a transaction and hashing them, apps can use the V2 messages endpoint with a transaction hash to get the message and attestation.
V2 offers Standard and Fast Transfer modes. Fast Transfer charges a variable fee based on the source chain.
The newer version also adds programmable hooks. These can trigger automatic actions on the destination blockchain after USDC arrives. CCTP V2 supports 27 blockchains and also handles the EURC stablecoin.
Some features do not carry over. The replaceDepositForBurn function has been removed with no V2 equivalent.
Circle also offers Arc App Kits as an optional tool. The kits handle routine contract address, interface, and attestation work for developers.
Circle has asked developers who run into problems to contact its team on Discord. As of this week, the October 31 limit cuts and the December 1 contract pause both remain on schedule.
The post <a href="https://blockonomi.com/circle-to-pause-legacy-usdc-cross-chain-protocol-on-december-1/" rel="noopener noreferrer nofollow">Circle to Pause Legacy USDC Cross-Chain Protocol on December 1</a> appeared first on <a href="https://blockonomi.com" rel="noopener noreferrer nofollow">Blockonomi</a>.

Circle to Pause Legacy USDC Cross-Chain Protocol on December 1

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