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DH
Dharmendra Nath Mishra Author
Original Post
6

Since the new NPCI 2-Factor Authentication (2FA) merchant login rules came into effect, I frequently get:

Error 55: Merchant Aadhaar Biometric Mismatch / Device Authentication Failed

Setup details:

  • Device: Mantra MFS100
  • OS: Windows 10

Due to this, my AePS terminal remains locked for the entire day. Has anyone found a permanent fix?

Which time of day do you usually complete your NPCI 2FA merchant biometric authentication?

459 votes

2 Responses

Accepted Solution / Best Answer
SA
Sanjay Nambiar Best Answer
13

Error 55 during merchant 2FA occurs because NPCI matches the live biometric capture against the BC agent Aadhaar demographic database with a stricter PID block threshold (minimum 65% quality score).

Ensure you are capturing the exact finger (usually right thumb or index) that has the highest biometric quality score in your bank's BC registration profile.

If unsure which finger was registered, contact your BC partner's onboarding team for the enrollment record.

Attachments:
NPCI_Circular_AePS_Daily_2FA_Merchant_Authentication.pdf (472 KB)
AN
Anand Swaroop Tiwari
#1
13

Technical checklist for Mantra MFS100 users:

  1. Uninstall old Mantra RD Service v1.0.4 and install:
    • Mantra RD Service v1.0.8
    • MFS100 Driver v9.2.0.0
  2. Navigate to C:\Program Files\Mantra\MFS100\Driver and run MFS100Test.exe as Administrator.
    • Verify Quality score is above 70.
  3. Ensure your PC date and time are synchronized: 
    Settings → Time & Language → Sync Now (time.windows.com)
    An offset of even 60 seconds causes UIDAI auth token expiration.
  4. If your skin is dry, press firmly or use a damp sponge before placing the finger on the prism.

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