Getting error 99 or app crash on testing environment

[kennguyen1506]

Describe the bug
I'm implementing momo payment for my webapp. However, I keep getting error 99 or the test app would crash when I try to make a test payment.
I made sure to make my payment request to the development server. So I'm not sure why this problem persists while all the fields are correct, and I'm getting the right response.

Would testing on production be different?

To Reproduce
Steps to reproduce the behavior:

1. Make payment request from my website with the correct body and header.
2. Redirect to momo payment gateway to scan QR code for authentication.
3. Using the test app to scan QR code.
4. See error 99, or the test app crashes.

Expected behavior
Expected to see transaction being processed without error. Or test app would not crash.

Screenshots
it either fails to process, or crash.

Desktop (please complete the following information):

• OS: [catalina]
• Browser [chrome]

Smartphone (please complete the following information):

• Device: [iPhone6s Plus]
• OS: [14.3]

Additional context