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Mastercard

Mastercard ECI Codes 00: 00

soft decline

Last updated: October 22, 2026

Key details

Brand
Mastercard
Code
00
Response
00
Detailed Response
Authentication failed or not attempted (e.g. card not enrolled, technical issue)
soft decline
This transaction is retriable

Payments failing with code 00 are often recoverable with the right retry timing and routing. SmartRetry recovers up to 70% of soft declines with smart retries!

Actually, a big part of your declined transactions can be recovered

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What it means

Mastercard ECI Code 00 is an indicator that 3D Secure authentication either failed or could not be attempted. It is not an authorization decline by itself, but rather a signal that the transaction lacks a successful 3DS authentication result. Because the transaction is not fully authenticated, merchants do not benefit from a chargeback liability shift.

Why does code 00 occur?

  • The cardholder's Mastercard is not enrolled in the 3D Secure program.
  • The issuer's Access Control Server (ACS) was unavailable or experienced a transient technical failure.
  • The cardholder failed the 3DS authentication challenge by entering incorrect information.
  • A configuration or technical problem on the merchant or gateway side prevented the authentication request.

How to solve 00?

First, inspect the raw 3DS result (such as Adyen's 'N' for not authenticated or 'U' for unavailable) to identify the specific root cause rather than relying solely on the ECI 00 indicator. If the issue was a failed challenge, ask the customer to re-authenticate while they are still in checkout. If the card is not enrolled, determine if your risk tolerance allows proceeding with a non-authenticated authorization, keeping in mind that fraud liability remains with your business. Fix any underlying gateway or configuration errors before initiating further requests.

Solving as a merchant

Review your gateway's underlying 3DS response logs to distinguish between technical failures, non-enrollment, and failed customer challenges. Apply your internal fraud and risk rules to decide if non-authenticated transactions should proceed to authorization. Ensure you do not automatically route already-unsuccessful 3DS attempts to secondary processors, as recommended by orchestration platforms.

Solving as a client

If prompted during checkout, carefully retry the 3D Secure challenge by verifying the one-time passcode or banking app notification. If the card is repeatedly unable to authenticate, contact the issuing bank to ensure the card is enrolled in 3D Secure, or use a different payment method.

Tip from SmartRetry Avoid queuing automated background retries for ECI 00, as submitting authorizations without valid authentication tokens risks immediate regulatory declines in SCA-enforced regions. Instead, configure real-time routing to prompt an in-session challenge or swap to an alternative payment method while the shopper is still active in checkout.

See the full list of Mastercard's decline codes >Find code on Mastercard's website >

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Kyle Regacho

Author

Kyle Regacho
LinkedInFind me on Linkedin

Focused on payment recovery, decline codes, and authorization optimization at SmartRetry. Helps payment teams turn failed transactions into recovered revenue

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Decline codes tell you why. We fix it.

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