Message type: E = Error
Message class:  CNV_DMC_SIN - Messages for s-innovations migration 
Message number: 018
Message text: Supply field "&2" , if indicator "... with fix. assignment" is set.
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_DMC_SIN018 typically occurs during data migration processes, particularly when using the SAP Data Migration Cockpit (DMC). This error is related to the supply field in the context of data mapping and transformation.
Cause: The error message indicates that there is an issue with the supply field (denoted as "&2") when the indicator "... with fix assignment" is set. This usually means that the system is expecting a specific value or mapping for the supply field, but it is either missing, incorrect, or not properly configured. The "fix assignment" indicator suggests that the system is trying to enforce a specific mapping or value that is not being met.
Solution: To resolve this error, you can follow these steps: Check the Mapping Configuration: Review the mapping configuration for the supply field in the data migration project. Ensure that the field is correctly mapped to the corresponding source field and that the values are
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV_DMC_SIN017 Access Plan Calculation for Migration Object &1 in process
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_DMC_SIN016 Access Plan Calculation finished for Migration Object &1
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_DMC_SIN101 Currency configuration of target company code &1 not available
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_DMC_SIN102 Source company code &1 not found in conversion rule
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.