How To Fix /SAPCND/CUSTOMIZING303 - Unknown RFC error

SAP Error Message - Details

• Message type: E = Error

• Message class: /SAPCND/CUSTOMIZING -

• Message number: 303

• Message text: Unknown RFC error

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 /SAPCND/CUSTOMIZING303 - Unknown RFC error ?

  The SAP error message /SAPCND/CUSTOMIZING303 Unknown RFC error typically indicates an issue with Remote Function Call (RFC) communication between systems in an SAP environment. This error can arise due to various reasons, including configuration issues, network problems, or authorization issues.
  Possible Causes:
  
  Network Issues: There may be connectivity problems between the SAP systems involved in the RFC call.
  RFC Destination Configuration: The RFC destination may not be correctly configured in transaction SM59. This includes incorrect parameters, such as the target system's IP address, port, or logon credentials.
  Authorization Issues: The user credentials used for the RFC connection may not have the necessary authorizations to perform the requested operation.
  System Availability: The target system may be down or not reachable due to maintenance or other issues.
  SAP Kernel or Patch Level: There may be a bug in the SAP kernel or a missing patch that affects RFC communication.
  
  Solutions:
  
  Check Network Connectivity: Ensure that the network connection between the systems is stable and that there are no firewalls blocking the RFC communication.
  Verify RFC Destination:
  
  Go to transaction SM59 and check the configuration of the RFC destination.
  Test the connection using the "Connection Test" button to see if it is successful.
  Ensure that the logon credentials are correct and that the target system is specified correctly.
  
  
  Review Authorizations: Ensure that the user used for the RFC connection has the necessary authorizations to execute the required functions.
  Check System Status: Verify that the target system is up and running. You can check the system status in transaction SM51 or by using the SAP GUI.
  Review SAP Notes: Check the SAP Support Portal for any relevant SAP Notes that may address known issues with the error message or provide patches.
  Check Logs: Review the system logs (transaction SM21) and the developer trace files (transaction ST11) for any additional error messages that may provide more context about the issue.
  
  Related Information:
  
  Transaction Codes:
  
  SM59: RFC Destinations
  SM21: System Log
  ST22: Dump Analysis
  ST11: Developer Traces
  SM51: List of SAP Systems
  
  
  SAP Notes: Search for relevant SAP Notes in the SAP Support Portal using keywords related to RFC errors or the specific error message.
  Documentation: Review SAP documentation on RFC communication and troubleshooting for more detailed guidance.
  
  If the issue persists after checking the above points, it may be necessary to involve your SAP Basis team or SAP support for further investigation.