3D Secure transaction block

we are using this
https://pay.sandbox.realexpayments.com/pay
but wen test card we get Transaction blocked by merchant's 3D Secure configuration

That error means your sandbox merchant is set to **block any transaction that isn’t 3-D Secure–authenticated** (for example: card not enrolled, auth unavailable, or failed challenge). Your HPP post is fine—the sandbox HPP URL `https://pay.sandbox.realexpayments.com/pay` is correct. citeturn4search12

### Fix it fast (sandbox)
1. **Relax your 3-D Secure rules in the portal**
– Log in to the **RealControl** (sandbox) merchant portal.
– Go to **Risk / 3-D Secure rules** (wording varies).
– Change outcomes like **Not Enrolled**, **Unavailable**, **Attempt**, or **Failed** from **Block** → **Hold** or **Allow** (for testing). Save.
This is exactly where “blocked by merchant’s 3-D Secure configuration” is coming from. citeturn4search1turn0search6

2. **Use the proper 3DS test cards & flows**
– Global Payments provides **test cards and an ACS simulator** so you can trigger **Authenticated**, **Attempt**, **Failed**, and **Challenge** outcomes. Use a card/scenario that returns **Authenticated** to avoid the block. citeturn0search1

3. **(Optional) Force a challenge for testing**
– If you need to see the challenge screen, set the HPP/3DS v2 parameter to request a challenge (challenge request indicator) per their 3DS2 docs. citeturn0search3

### Quick checklist
– ✅ Posting to sandbox HPP: `pay.sandbox.realexpayments.com/pay`. citeturn4search12
– ✅ 3DS v2 enabled on your sandbox merchant (support can enable if missing). citeturn0search4
– ✅ 3DS rules not set to “Block” for non-auth scenarios during testing. citeturn0search6
– ✅ Use Global Payments’ 3DS **test cards** to simulate “Authenticated”. citeturn0search1

If you want, tell me your current rule values (Not Enrolled / Unavailable / Failed), and I’ll suggest exact settings for safe sandbox testing.