UPI error U18: ReqAuth acknowledgement not received
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
NPCI sent a request authorisation (ReqAuthDetails) to the payee PSP but didn't get an acknowledgement back.
Not fully documented: NPCI doesn't document the step; ReqAuthDetails runs before the debit in the standard flow.
No. This decline happens before your account is debited.
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.
NPCI's UPI switch.
Technical: a system didn't respond or failed.
What you should do
Wait a few minutes and try again, or use another UPI app. Check your statement first in case money left your account.
If you are a merchant, bank or PSP
The payee PSP didn't acknowledge ReqAuthDetails. Check its endpoint and timeouts.
UPI error U18 kya hai?
U18 ka matlab hai receiver ke PSP ne authorisation request ka jawab nahi diya.
Related codes
If it still isn't sorted
- 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.
- If the app doesn't resolve it, contact your bank's grievance desk with the same reference.
- 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.