Error
Error Code:
1027
SAP S/4HANA Error 1027: Communication Initialization Failure
Description
Error 1027, ERR_COM_INIT, indicates a failure in initializing a critical communication channel within or between SAP S/4HANA components. This typically occurs during system startup, module activation, or when attempting to connect to integrated external systems, preventing essential business processes from executing.
Error Message
ERR_COM_INIT
Known Causes
4 known causesNetwork Connectivity Problems
The SAP S/4HANA system or its communicating component cannot reach the target host due to network outages, firewall blocks, or incorrect network configurations.
Misconfigured Communication Settings
Essential communication parameters, such as hostnames, port numbers, or protocol settings, are incorrectly defined within SAP S/4HANA or the external system's configuration.
Authentication or Authorization Failure
The system attempting to establish communication lacks the necessary user credentials, digital certificates, or proper authorization roles to connect securely.
Dependent Service Unavailable
A required background service, gateway, or external component that SAP S/4HANA needs to communicate with is not active or has crashed.
Solutions
4 solutions available1. Verify SAP Gateway Service Configuration easy
Ensures the SAP Gateway (GW) services required for S/4HANA communication are running and accessible.
1
Log in to your S/4HANA system using SAP GUI.
2
Execute transaction code `SMGW` (Gateway Monitor).
3
Check the status of the Gateway. If it's not running, attempt to start it from the `SMGW` menu: Goto -> Start Gateway.
4
Navigate to `SM59` (RFC Destinations).
5
Identify and test RFC destinations that are critical for S/4HANA communication, especially those pointing to the Gateway or other SAP systems. Look for destinations of type 'T' (TCP/IP) and '3' (ABAP Connection).
6
Use the 'Connection Test' and 'Unicode Test' buttons for each relevant RFC destination. Resolve any connection errors reported.
2. Check Network Connectivity and Firewall Rules medium
Confirms that the S/4HANA application servers can reach the required communication endpoints and that no firewalls are blocking traffic.
1
Identify the IP addresses and ports used by the SAP S/4HANA application servers, the SAP Gateway, and any external systems it needs to communicate with.
2
From a command prompt or terminal on the S/4HANA application server (or a server that can initiate the communication), use `ping` to test basic network reachability to the target systems.
ping <target_ip_address>3
Use `telnet` or `nc` (netcat) to test connectivity to specific ports. For example, to test port 3300 (SAP Gateway default):
telnet <target_ip_address> 3300
# or
nc -zv <target_ip_address> 33004
Collaborate with your network administrators to review firewall rules on all intermediate network devices and the target servers. Ensure that the necessary ports (e.g., SAP Gateway port, HTTP/HTTPS ports for OData services) are open for traffic between the S/4HANA servers and their communication partners.
5
If S/4HANA is hosted in a cloud environment (e.g., AWS, Azure, GCP), verify security group or network access control list (NACL) rules.
3. Restart SAP Gateway and Application Server Instances easy
A simple restart can often resolve transient communication issues and re-initialize communication components.
1
Log in to the operating system of your S/4HANA application server.
2
Identify the SAP instance name (e.g., `S4H`).
3
Stop the SAP Gateway process. The command might vary slightly depending on your OS and SAP installation, but typically it involves the `gwrd` process.
sudo <sapsid>
stop
gw4
Stop the SAP application server instance(s).
sudo <sapsid>
stop
<instance_number>5
Start the SAP application server instance(s) in the correct order (e.g., enqueue server, message server, then work processes).
sudo <sapsid>
start
<instance_number>6
Start the SAP Gateway process.
sudo <sapsid>
start
gw7
Verify that all SAP processes are running using `ps -ef | grep <sapsid>` or the SAP Management Console (SMC).
4. Review SAP Trace Files and System Logs medium
Investigates detailed error messages in SAP trace files and the system log to pinpoint the root cause of the communication failure.
1
Access the S/4HANA application server's file system.
2
Navigate to the SAP work directory, typically located at `/usr/sap/<SAPSID>/<INSTANCE_NAME>/work/`.
3
Examine the `dev_rd` trace file (Gateway trace) for errors related to communication initialization. Look for keywords like 'ERR_COM_INIT', 'connection failed', or network-related errors.
tail -f dev_rd4
Check the `dev_w<n>` trace files (work process traces) for errors that might occur when a work process attempts to establish a communication.
tail -f dev_w<n> # where <n> is the work process number5
In SAP GUI, execute transaction `SM21` (System Log) to view system-wide messages. Filter by error messages or messages occurring around the time of the `ERR_COM_INIT` error.
6
If the error occurs during an RFC call, check the trace files associated with the RFC client or server, which can be found in the work directory.
7
Use the `ST05` (Performance Trace) transaction in SAP GUI to trace specific RFC calls if the issue is intermittent or related to a particular transaction.