How To Fix PO745 - Host &1 is unknown (See system log)

SAP Error Message - Details

• Message type: E = Error

• Message class: PO - Spooler message

• Message number: 745

• Message text: Host &1 is unknown (See system log)

Self-Explanatory Message

Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.

To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.

Unfortunately, there isn't any extra information in this error notice.

What else can you do?

First, use our AnswerBot below to get a possible cause and solution (requires a premium subscription).

Also, review the in-depth Common Questions & Answers listed below; you could discover a solution there or be able to connect with others who have faced similar challenges.

You can also try searching the SAP support portal (support.sap.com) but you need a special user ID to access it. It is possible that an SAP support note exists that provides additional details about the mistake or even steps for fixing it.

Smart SAP Assistant

• What is the cause and solution for SAP error message PO745 - Host &1 is unknown (See system log) ?

  The SAP error message PO745 "Host &1 is unknown (See system log)" typically indicates that the system is unable to resolve the hostname specified in the configuration or the network settings. This can occur in various scenarios, such as when trying to connect to a database, an external system, or during communication between different SAP instances.
  Causes:
  
  Incorrect Hostname: The hostname specified in the configuration is incorrect or misspelled.
  DNS Issues: The Domain Name System (DNS) is unable to resolve the hostname to an IP address.
  Network Configuration: There may be network issues preventing the SAP system from reaching the specified host.
  Host Not Available: The target host may be down or not reachable due to network issues.
  Firewall Restrictions: Firewalls may be blocking access to the specified host.
  
  Solutions:
  
  Check Hostname: Verify that the hostname specified in the configuration is correct. Ensure there are no typos or incorrect entries.
  DNS Configuration: Check the DNS settings on the SAP server. You can use commands like nslookup or ping to test if the hostname resolves correctly.
  Hosts File: If DNS is not configured, you can add the hostname and its corresponding IP address to the /etc/hosts file (on Unix/Linux) or C:\Windows\System32\drivers\etc\hosts (on Windows).
  Network Connectivity: Ensure that the network connection is stable and that the SAP system can reach the target host. You can use tools like ping or traceroute to diagnose connectivity issues.
  Firewall Settings: Check if there are any firewall rules that might be blocking access to the specified host. Adjust the firewall settings as necessary.
  System Log: Review the system log (transaction SM21) for more detailed error messages that might provide additional context about the issue.
  
  Related Information:
  
  Transaction Codes: Use transaction codes like SM21 (System Log), SM37 (Job Monitoring), and ST22 (Dump Analysis) to gather more information about the error.
  SAP Notes: Check the SAP Support Portal for any relevant SAP Notes that might address this specific error or provide additional troubleshooting steps.
  Network Tools: Familiarize yourself with network diagnostic tools that can help in troubleshooting connectivity issues, such as ping, traceroute, and telnet.
  
  By following these steps, you should be able to identify and resolve the underlying cause of the PO745 error in your SAP system.