3211420 - Error "while trying to invoke the method net.minidev.json.JSONObject.toJSONString() of a null object loaded from local variable 'json'" while reading groups from SuccessFactors by IPS

In IPS, the group synchronization from SuccessFactors source system is enabled.
In the IPS job log, the following error occurred when read groups from SuccessFactors system.

org.quartz.JobExecutionException: Cannot execute provisioning job in tenant context: <id> 
Caused by: com.sap.cloud.ips.connector.exception.ProvisioningRuntimeException: Error during execution on behalf of tenant with ID: <id> 
Caused by: com.sap.cloud.ips.runtime.exception.ProvisioningException: Executing delta load failed. 
Caused by: com.sap.cloud.ips.connectors.api.ConnectorException: Connector cannot process more entities due to irreparable error 
Caused by: com.sap.cloud.ips.connectors.api.CallbackFatalException: Cannot post process group resource '<group name>' 
Caused by: java.lang.NullPointerException: while trying to invoke the method net.minidev.json.JSONObject.toJSONString() of a null object loaded from local variable 'json'

Identity Provisioning

SF, IPS, group , KBA , BC-IAM-IPS , Identity Provisioning Service (IPS) , Problem