Why am I getting a merchant_id / merchant_key error?

Why am I getting a merchant_id / merchant_key error?

This may be due to using your live Merchant ID and Key for the sandbox. When testing in sandbox, you can either use our default sandbox credentials or you can use your own unique sandbox credentials.

For sandbox credentials without a passphrase:
Merchant ID: 10000100
Merchant Key: 46f0cd694581a

For sandbox credentials with a passphrase:
Merchant ID: 10004002
Merchant Key: q1cd2rdny4a53
Passphrase: payfast

To generate your own unique credentials, you will need to create your own sandbox account. To do this, navigate to https://sandbox.payfast.co.za/ and register using your email address. On the sandbox dashboard, you will be given your unique sandbox Merchant ID and Key, and this will remain associated with the email used to log in. You will also be able to set a passphrase on your sandbox account.