I have the same problem.
Can your team help me too?
I have got an Authentication failed. API credentials are incorrect error While Accepting the Bid.
I have Checked all the possible steps to check if the Paypal settings are not good
But every thing seems Okay
I was having trouble with this step also, but found out what i was doing wrong.
Are currently in test mode, and are your settings in the Payment gateway set to “Enabled” under “Payment Test Mode”?
If they are, you need to use the Sandbox API credentials. The Paypal sandbox feature is purely for testing only, and no transactions will actually be made. If you are running your site live, you use the API credentials in your PayPal account (be sure to check “Payment Test Mode” to disabled if that’s the case).
To get your API credentials for Sandbox, go to www.developer.paypal.com and log in.
Hope this clears it up for someone. It’s been a pain for me, but finally got past this step.
Now i am getting error “Invalid request parameter: email cannot be blank”, when trying to accept a bid (in test mode). Any guidance from here would be amazing!