UPI error codes / U66
UPI response code

UPI error U66: Device fingerprint mismatch

Official NPCI descriptionDEVICE FINGERPRINT MISMATCH BUSINESS

Raised by: NPCI UPI switch. Source: NPCI, UPI Error and Response Codes v2.9, section 4.4, errors from the UPI service layer.

What it means

The device fingerprint didn't match the one registered for your UPI profile, so NPCI treats the request as coming from an unrecognised device.

Was money deducted?

No. This decline happens before your account is debited.

When does the money come back?

Nothing to refund in the normal case. If a debit does show on your statement, the bank must reverse it by T+1 for a transfer to a person, or T+5 for a payment to a merchant.

Which side caused it?

NPCI's UPI switch.

Type of decline

Business: the systems worked and declined the payment.

If money left your account. Under RBI's turnaround-time rules (circular DPSS.CO.PD No.629/02.01.014/2019-20, 20 September 2019), if your account is debited but the payment fails, the money must come back by the next working day (T+1) for a transfer to a person, or within T+5 days for a payment to a merchant. After that the bank owes you ₹100 for every day of delay.

What you should do

If you changed phone, reinstalled the app or changed SIM, re-register the UPI app on this phone with the SIM linked to your bank account.

If you are a merchant, bank or PSP

Prompt the user to re-register their device. NPCI calls this a business decline, so don't retry.

UPI error U66 kya hai?

U66 ka matlab hai phone ki pehchaan match nahi hui; app dobara register karein.

Related codes

ZFTransaction not permitted to deviceU63Device registration failedB1Registered mobile number changedU65Device registration creds block errorU16Risk threshold exceeded

If it still isn't sorted

  1. Raise a complaint inside your UPI app. Every UPI app has a help or dispute option on the transaction, and it goes into NPCI's online dispute system. Keep the UPI transaction ID or RRN handy.
  2. If the app doesn't resolve it, contact your bank's grievance desk with the same reference.
  3. If your bank hasn't replied within 30 days, or you're not happy with the reply, complain to the RBI Ombudsman at cms.rbi.org.in. It's free.

Technical or business decline?

NPCI splits declines into two kinds. A technical decline means a system didn't respond or failed: a bank offline, a timeout, a switch error. A business decline means the systems worked and said no, for a reason about the account or the payment: wrong PIN, not enough money, a limit, a risk check. Retrying helps with some technical declines and almost never with business ones.

See all 216 UPI error codes →