Message type: E = Error
Message class:  S_CUS_IMG_ACTIVITY - IMG Activity 
Message number: 131
Message text: IMG activity &1 is an SAP object
The IMG activity &V1& was delivered by SAP.
Any changes you make to the BC Set attributes of the object can be
overwritten by a new delivery by SAP.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message S_CUS_IMG_ACTIVITY131 indicates that the IMG (Implementation Guide) activity you are trying to access is an SAP object and cannot be modified or customized. This typically occurs when you attempt to make changes to standard SAP configuration settings that are not intended to be altered.
Cause: Standard SAP Object: The activity you are trying to access is a standard SAP object, which means it is part of the core SAP system and is not meant to be customized directly. Authorization Issues: You may not have the necessary authorizations to perform the action you are attempting. Incorrect Path: You might be trying to access the IMG activity through an incorrect path or transaction.
Solution: Check the Activity: Verify if the IMG activity you are trying to access is indeed a standard SAP object. You can do this by checking the documentation or SAP notes related to that specific activity. Use Customizing Requests: If you need
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
S_CUS_IMG_ACTIVITY130 Customizing object &1 is an SAP object
What causes this issue?  The customizing object &V1& was delivered by SAP. Any changes you make to the BC Set attributes of the object can be ...
S_CUS_IMG_ACTIVITY129 IMG activity &1 and customizing object &2 are SAP objects
What causes this issue?  The IMG activity &V1& and the customizing object &V2& were delivered by SAP. Any changes you make to the BC S...
S_CUS_IMG_ACTIVITY132 Table &1 contains forbidden key field ('&2' has > 255 characters)
What causes this issue?  Table/view &V1& contains key fields which are more than 255 characters long.System Response  You cannot use the objec...
S_CUS_IMG_ACTIVITY133 Table &1 contains forbidden key field '&2' of type String
What causes this issue?  The table/view &V1& contains key fields of type 'STRING' or 'XSTRING'.System Response  You cannot...
Click on this link to search all SAP messages.