Circle will start throttling the legacy Cross-Chain Transfer Protocol (CCTP V1) on Saturday, October 31.The wind-down will end Dec. 1, 2026, at which point V1 contracts stop.Apps still using USDC in the old system have about a month to change over to CCTP V2. Otherwise, their crosschain transfers will end.Burn limits drop from October 31 until a December 1 pauseCCTP links USDC across blockchains. On one chain, it burns the stablecoin and mints that much on another chain. To clear the mint, Circle needs to sign off on it, which is called an attestation.There is a burn limit that tells the process how much USDC it can take in at any given time. In a blog post on August 27, Circle said that these limits would start to be lowered on October 31. Performance would get worse over the course of one month in order to get rid of all legacy use.Circle’s CCTP V1 wind-down schedule, from its August 27, 2026 migration post.The V1 contracts will stop on December 1. Integrations still linked to them then can’t move USDC between chains.Circle first warned about the move away from V1 on November 14, 2025.Since Noble won’t get CCTP V2, it’s on a different schedule. New USDC minting there was set to close on October 13.The Noble USDC contract and all its CCTP routes will stop working on January 12, 2027. Manual redemptions open a day later.Circle now lists Sui on V2, and all V1 chains except Noble already use V2.CCTP V2 adds three parameters to depositForBurnPlain CCTP, which used to be called CCTP V2, has its own contracts and APIs and can’t work with V1.TokenMessengerV2 and MessageTransmitterV2 are two of the new interfaces that developers will need to change the code to point to. There are three extra parameters in V2’s depositForBurn function: a destination caller, a maximum fee, and a minimum finality threshold.Instead of getting message bytes from an onchain transaction and hashing them, integrations ask for them at a V2 messages API with the transaction hash.It is no longer possible in V2 to use replaceDepositForBurn or some other old functions. Developers no longer have to worry about contract addresses and attestation polling when they use Circle’s Arc App Kits.V2 adds Standard and Fast Transfer modes and supports 31 blockchains. When USDC comes, programmable hooks let an app start an automatic action on the destination chain.How much Fast Transfer costs is based on the source chain. There was no fee for transfers on V1.Circle says that there will be more minter allowances than pending attestations so that in-flight transfers can be settled before the pause on December 1.CCTP has come under legal fire before. A Drift Protocol investor filed suit against Circle in a Massachusetts district court in April in connection with the $280 million Drift exploit, Cryptopolitan reported.The class action claims that Circle didn’t freeze around $230 million of USDC that North Korean hackers channeled through CCTP. CEO Jeremy Allaire said Circle freezes wallets at the direction of law enforcement or courts and should not be a digital vigilante.Circle launched its Arc layer-1 blockchain on mainnet in September with validators including BlackRock, Visa, Mastercard and DTCC.Don’t just read crypto news. Understand it. Subscribe to our newsletter. It's free.