Message type: E = Error
Message class:  CRMS4_SOM_PROD_BO - Messages for BO Subscription Product Specification 
Message number: 052
Message text: Maintain BRFplus function for external object '&1'
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 CRMS4_SOM_PROD_BO052 indicates that there is an issue with the Business Rule Framework plus (BRFplus) function related to an external object in the SAP system. This error typically arises when the system is unable to find or properly maintain the BRFplus function that is required for processing a specific external object.
Cause: Missing BRFplus Function: The specified BRFplus function for the external object is not defined or is missing in the system. Incorrect Configuration: The configuration for the BRFplus function may not be set up correctly, leading to the inability to access or execute the function. Authorization Issues: The user may not have the necessary authorizations to access or maintain the BRFplus function. Transport Issues: If the BRFplus function was recently transported from another system, there may have been issues during the transport process.
Solution: Check BRFplus Function: Go to the BRFplus workbench (transaction code BRF+). Verify if the function for the external object is defined
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CRMS4_SOM_PROD_BO051 Maintain BRFplus function for numeric parameter '&1' (charge plan '&2')
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CRMS4_SOM_PROD_BO050 Maintain BRFplus function for string parameter '&1' (charge plan '&2')
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CRMS4_SOM_PROD_BO053 Maintain BRFplus function for date parameter '&1' (ext. object '&2')
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CRMS4_SOM_PROD_BO054 Maintain BRFplus function for string parameter '&1' (ext. object '&2')
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.