3586976 - EC-to-ECP: Error Code: 201 - Error Message: The system failed to generate the access token' while opening Direct Pay Statement.

While opening Direct Pay Statement from employee's profile in EC, the error:

• Error Code: 201
• Error Message: The system failed to generate the access token.

This may also happen in the Payroll System Information screen. 

• SAP SuccessFactors Employee Central Payroll 

Employee Central Payroll, OAuth, Error ID, Gateway Service, Payroll System Information, Direct Pay Statement, 201, The system failed to generate the access token, We're Sorry.... but the page you requested was not found (error code 404), Exception was Attribute 'Recipient' of element 'SubjectConfirmationData' is invalid, Received fatal alert: certificate_unknown
Received fatal alert: certificate_expired, No OAuth 2.0 client authentication credentials included or used authentication method is unsupported, For OAuth 2.0 client EC_ESS_OAUTH, the authentication method CERTIFICATE was deactivated, The requested URL /sap/bc/sec/oauth2/token was not found on this server, OAuth 2.0 Client authentication failed, OAuth 2.0 client is unknown, Internal server error occurred, Exception was No user found with alias ' **** ' (format: unspecified), Exception was Error in ST program SAML2_ASSERTION when importing XML data, Exception was There is no trust between entities and www.successfactors.com in client xxx, Exception was Entity https://yourPayrollSystem/sap/bc/ is not defined in the element 'AudienceRestriction', Exception was No user found for name ID ' ***** ' (format: unspecified), Exception was Format 'urn:oasis:names:tc:SAML:1.1:nameid-format:unspecif' is not supported for user assignment, For OAuth 2.0 client EC_ADM_OAUTH, the authentication method BASIC was deactivated OR For OAuth 2.0 client EC_ESS_OAUTH, the authentication method CERTIFICATE was deactivated, Authenticated OAuth 2.0 client is not configured to use this authorization grant type: urn:ietf:params:oauth:grant-type:saml2-bearer, Requested OAuth 2.0 scope exceeds the scope granted by the resource owner or OAuth 2.0 client, Service cannot be reached. URL call was terminated because the corresponding service is not available, The requested OAuth 2.0 scope cannot be granted because it is either not assigned to the current user or to the OAuth 2.0 client , KBA , LOD-EC-ECP-SF-PST , EC Payroll Pay Statement , Problem