Japanese cryptocurrency exchange Coincheck suspended all cryptocurrency deposits in the early hours of Thursday, November 5, 2026, after a third-party analytics service it uses to screen transactions stopped working. The company said the disruption was not caused by a breach and that no one gained access to customer funds. It is also a window into an operational dependency that rarely makes headlines: when outside compliance tooling fails, core exchange functions can halt even when — as here — the exchange reports no breach of its own systems.

No unauthorized access, Coincheck says

Coincheck detailed the disruption in an official notice. According to the post, processing of crypto deposits and withdrawal requests began to lag at around 00:04 Japan time on Thursday, November 5, 2026, after the external on-chain analysis service used to screen transactions failed. The exchange said via its X account that the problem was first spotted at 3:09 a.m.

The exchange canceled new and pending withdrawal requests. Some requests will be reviewed immediately once systems are back online, while funds from canceled requests will be returned to users' account balances. Incoming transfers remain delayed.

Coincheck made clear that the outage was the fault of its external service provider. The notice, originally written in Japanese, translates into English as: "This issue was caused by a failure in an external service we use, and there has been no unauthorized access or incident affecting our customers' assets."

The statement indicates there was no hack and no unauthorized access to customer assets, and that deposits remain safe.

An external on-chain analysis tool at the center

Coincheck did not name the third-party provider, but said it was an external on-chain analysis service used to screen crypto receipts and transfers. Chainalysis provides that type of service to exchanges through its Know Your Transaction (KYT) product, which monitors crypto movements for illicit activity. Screening tools of this kind are embedded in standard exchange compliance workflows, checking transactions against databases of suspicious addresses before funds are credited — a structure that explains how a vendor failure alone can stall deposit processing even when an exchange reports no breach.

On November 4, 2026 — one day before the Coincheck disruption — Chainalysis took KYT offline, along with its other address-screening products and its login page, after flagging abnormal activity. The company said it planned to bring KYT back online and restore screening the following day.

For now, any connection between the two events is mere speculation, as neither firm has publicly linked them.

A Chainalysis breach running in the background

The suspension comes as Chainalysis continues to deal with a widening cyberattack it disclosed last week. The firm has reported that an attacker obtained the personal details of all users on its platform and has advised users to reset passwords and rotate API keys. Affected customers include law enforcement agencies, regulators, and national security bodies — a measure of how widely this kind of screening infrastructure is used across both government and the private sector.

The attack was first reported on October 30, although there was no evidence of personal data theft at the time. Chainalysis says offensive agentic techniques are responsible for the attacks, while noting the incident is completely different from the $6.3 billion Binance theft last week, the largest crypto hack on record.

Why Coincheck is quick to rule out a hack

Coincheck's history makes the company quick to rule out a breach. In January 2018, the exchange paused withdrawals after hackers stole roughly 500 million NEM tokens, worth approximately $530 million at the time — then one of the biggest crypto thefts ever. That theft triggered on-site inspections by Japan's Financial Services Agency and ended with Coincheck's acquisition by online broker Monex Group later the same year.

The firm said it will announce when the current issue is resolved and withdrawals reopen, and asked affected users to resubmit transfer requests after service returns. Two updates are worth watching from here: Coincheck's promised notice once service is fully restored, and Chainalysis's stated plan to bring its KYT screening back online. Until that notice arrives, incoming transfers at Coincheck stay delayed — with the exchange maintaining that customer assets were unaffected.