Message type: E = Error
Message class:  CNV_MBT - PCL message class 
Message number: 502
Message text: Variant & is not defined for selection group & in package &
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 CNV_MBT502 typically indicates that a specific variant is not defined for a selection group in a particular package during a data migration or conversion process. This error is often encountered in the context of SAP's Migration Cockpit or during data transfer processes.
Cause: Missing Variant Definition: The variant specified in the error message is not defined in the system for the selection group mentioned. Incorrect Configuration: The selection group or package may not be correctly configured, leading to the system not recognizing the variant. Transport Issues: If the variant was supposed to be transported from another system, it may not have been included in the transport request. Authorization Issues: Sometimes, the user may not have the necessary authorizations to access the variant or selection group.
Solution: Check Variant Definition: Go to the transaction where the variant is supposed to be defined (e.g., SE38 for ABAP programs). Check if the variant exists for the specified selection
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV_MBT501 Selection group & has no assigned variant in package &
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_MBT500 Selection group & does not exist in package &
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_MBT503 Option & is not allowed as select option (Sel.grp/Set/member) &/&/&
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_MBT504 Error while generating group & in package & (sy-subrc &)
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.