Unable to retrieve access token

What causes this issue?

When using three-legged OAuth an access token has to be used. If none is
available for the current user<(>,<)> a new token is requested from the
service provider. This request failed and did not return an access
token.

System Response

The function cannot be executed.

How to fix this error?

One reason might be that the service provider is offline for a short
period or some other connection problem. Try again later.

Procedure for System Administrators

Check if the credentials for three-legged OAuth authentication are met:
An OAuth client has to be registered with the service provider
This client must have a trusted relationship to this system using the
certificate from an SSF application named CLBOAU
When using a SAML assertion to authenticate<(>,<)> the user the SAML
provider has to be enabled on this system
The IDP named in the SAML2 transaction has to be made known in the
service provider settings.

Error message extract from SAP system. Copyright SAP SE.