3723823 - EC to ECP Data Replication: Authentication service failed to return token

While replicating Employee Master Data or Employee Time Data using the batch job/scheduled job, the following error is raised in SLG1:

Error:
Code: AuthenticationFailed
Message: Authentication service failed to return token.
Details: Only support OAuth/OIDC authentication type.

However, while performing a Manual Master Data or Time Data replication, a different error could appear in SLG1:

Error:
Code: AuthenticationFailed
Message: Authentication service failed to return token.
Details: [AUTH0032]Invalid client certificate

NOTE: the error appears in SLG1 with the following JSON structure:

Login response: {"error":{"code":"&1","message":"&2","details":&3"}} 
Employee Central login failed. Aborted employee replication based on configuration query.

• Employee Master Data Replication from Employee Central to Employee Central Payroll
• Employee Time Data Replication from Employee Central to Employee Central Payroll
• SAP SuccessFactors Employee Central Payroll

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