My question is nearly identical to
https://www.paypal-community.com/t5/REST-APIs/PayPal-IdentityException-The-remote-server-returned-an...
but I will explain what the difference is.
It's my first time consuming the PayPal API. I'm following the Quick Start at GitHub https://github.com/paypal/PayPal-NET-SDK/wiki/Quick-Start
My app.confg file
<paypal>
<settings>
<add name="mode" value="sandbox" />
<add name="clientId" value="***" />
<add name="clientSecret" value="***" />
</settings>
</paypal>
My C# code is executing from a test class. The relevant (failing) part of the code is
var config = ConfigManager.Instance.GetProperties(); //returns a dictionary with 3 items
var accessToken = new OAuthTokenCredential(config).GetAccessToken(); // fails
Examining the exception shows it is an Identity Exception, and the response is
"{\"error\":\"invalid_client\",\"error_description\":\"Client Authentication failed\"}"
Sadly, this is where I'm now lost. I understand it is saying the issue is the client is invalid, and as such, I initially guessed I have probably provided the wrong ClientID, but I don't feel this is the case.
Within PayPal -> All Tools -> API Credentials I click on Manage API credentials, authenticate myself and see my Client ID and Client Secret. I copy and paste these into my app.config file but the same error messages persists.
Another look at https://github.com/paypal/PayPal-NET-SDK/wiki/Configuration shows that I need to have built a webapp. Sadly, the links in that document do not work so, I'm now lost. Am I supposed to get the auth details as I described above, or do I still need to create a webapp within PayPal?
