Error
Error Code:
599
SAP S/4HANA Error 599: API Session Not Initialized
Description
Error 599, ERR_API_NOT_INITIALIZED, indicates that an attempt was made to use an SAP S/4HANA API or session-dependent functionality before the underlying session layer was properly established. This typically occurs during application startup, module loading, or when a new user session is being created or resumed within the system.
Error Message
ERR_API_NOT_INITIALIZED
Known Causes
4 known causesImproper Application Initialization
The SAP S/4HANA application or a connected module attempted to call an API before its required session layer components had fully loaded and initialized.
Concurrent Session Access
Multiple processes or threads tried to access the same session or API endpoint simultaneously, leading to a race condition where the session wasn't ready for one of the calls.
Incorrect Configuration
Underlying system or application configuration settings are preventing the session layer from initializing correctly or in a timely manner.
Resource Loading Delays
Network latency or temporary resource unavailability caused delays in loading critical session components, leading to premature API calls.
Solutions
4 solutions available1. Restart the SAP Gateway Service easy
A common cause is a temporarily unresponsive SAP Gateway service, which manages API communication.
1
Log in to your SAP S/4HANA application server as an administrator.
2
Access transaction SMGW (Gateway Monitor).
3
Navigate to 'Goto' -> 'Expert Functions' -> 'Troubleshooting' -> 'Restart Gateway'.
4
Confirm the restart when prompted.
5
Attempt the API call again after the gateway has restarted.
2. Verify RFC Destination Configuration medium
Incorrect or missing RFC destinations can prevent proper API session initialization.
1
Log in to your SAP S/4HANA system.
2
Access transaction SM59 (RFC Destinations).
3
Identify and check RFC destinations relevant to the API being used. Common types include 'G' (Registered Server Program) and '3' (ABAP System).
4
For each relevant RFC destination, perform a 'Connection Test' and 'Unicode Test' (if applicable).
5
If tests fail, review the configuration parameters, including Program ID, Gateway Host, and Gateway Service, ensuring they match the target system's configuration.
6
Ensure the SAP Gateway on the target system is running and accessible.
3. Check SAP Gateway Security Settings advanced
Gateway security configurations might be blocking the API session initialization.
1
Log in to your SAP S/4HANA application server.
2
Access transaction SMGW.
3
Navigate to 'Goto' -> 'Security Settings'.
4
Review the registered programs and access control lists (ACLs). Ensure that the program ID used by the API client is registered and allowed to connect.
5
If necessary, update the ACLs to permit the required connections. Be cautious when modifying security settings to avoid compromising system security.
6
After any modifications, restart the SAP Gateway service (as per Solution 1) for the changes to take effect.
4. Examine SAP Gateway Trace Files advanced
Detailed trace files can reveal the root cause of the API session initialization failure.
1
Log in to your SAP S/4HANA application server.
2
Access transaction SMGW.
3
Navigate to 'Goto' -> 'Trace' -> 'Gateway'.
4
Set the trace level to a higher value (e.g., Level 2 or 3) to capture more detailed information.
5
Reproduce the error by attempting the API call again.
6
Navigate back to 'Goto' -> 'Trace' -> 'Display' to view the generated trace file.
7
Analyze the trace file for error messages, connection issues, or security-related rejections. This often provides specific clues about the failure.
8
If the trace analysis is complex, consider engaging SAP Basis or security teams for assistance.