Hi @MADCOMMERCE
Authentication failed means “Wrong paypal credentials”
To resolve, please check that you added your PayPal credentials correctly:
- If doing test purchases (test mode ON): use your sandbox credentials
- If doing live purchases (test mode OFF): use your real credentials
We suggest deleting the gateway and then adding it again. When doing this, make sure that you copied the whole client id and secret key and pasted it without pressing the tab key or adding extra spaces as this can also lead to issues.
The test mode on/off can be set up from Funnel Settings:
