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Mastercard

Mastercard ECI Code 01: Attempted Authentication

Last updated: October 8, 2026

Key details

Brand
Mastercard
Code
01
Response
01
Detailed Response
Authentication was attempted but not completed (e.g. timeout, user abandon)

What it means

Mastercard ECI Code 01 is an informational indicator showing that a payer-authentication flow was initiated, but the cardholder authentication could not be fully completed (typically PARes status 'A'). It is an authentication indicator passed to the subsequent authorization, rather than an authorization decline itself.

Why does code 01 occur?

  • The cardholder abandoned the checkout process while the 3D Secure authentication window was open.
  • The authentication session timed out before the customer could successfully verify their identity.
  • Authentication was unavailable because the specific card or issuer is not currently participating in the program.

How to solve 01?

No resolution is required as this is not a decline. Simply pass this ECI code along with the corresponding authentication data (such as the directory-server transaction ID and UCAF data) into your authorization request to proceed with the transaction.

Solving as a merchant

Ensure your 3D Secure integration correctly captures and passes this ECI code and any associated authentication data into the final authorization request.

Solving as a client

No action is required from the customer for this informational status.

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

Frequently asked questions about this topic

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Kyle Regacho

Author

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

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