Message type: E = Error
Message class:  U6 - Message Class for BRE 
Message number: 134
Message text: Enter a backlog set for BRE run
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.
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.
The SAP error message U6134, which states "Enter a backlog set for BRE run," typically occurs in the context of the Business Rules Engine (BRE) in SAP. This error indicates that the system requires a backlog set to be specified before executing a BRE run.
Cause: The error is caused by the absence of a backlog set in the configuration or during the execution of a BRE process. A backlog set is a collection of rules or conditions that need to be processed, and without it, the system cannot proceed with the BRE run.
Solution: To resolve this error, you can follow these steps: Check Configuration: Ensure that the backlog set is properly configured in the system. You may need to navigate to the relevant configuration settings in the SAP system to verify this. Create a Backlog Set: If a backlog set does not exist, you will need to create one. This can typically be done
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
U6133 No entries in table &1 for activity &2
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
U6132 Table &1: Error deleting, or data to be deleted not found
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
U6135 Caution: Deletion report
What causes this issue?  This program deletes the fields for agent determination in the error extract table (INSTSET). If you use the agent determinat...
U6136 Activity category &1 not permitted for backlog reduction engine
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
Click on this link to search all SAP messages.