Message type: E = Error
Message class:  CNV_NCE_BAS - Number conversion engine: messages 
Message number: 402
Message text: Display mode activated
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_NCE_BAS402 Display mode activated" typically occurs in the context of data migration or conversion processes, particularly when using the SAP S/4HANA Migration Cockpit or similar tools. This message indicates that the system is currently in "display mode," which means that certain actions, such as data changes or updates, cannot be performed.
Cause: Display Mode Activation: The system is set to display mode, which is often a protective measure to prevent accidental changes during critical processes. User Permissions: The user may not have the necessary permissions to switch from display mode to edit mode. Configuration Settings: The configuration of the migration or conversion tool may be set to display mode due to specific settings or parameters.
Solution: Switch to Edit Mode: If you have the necessary permissions, look for an option to switch from display mode to edit mode. This is usually found in the toolbar or menu options of the migration tool. Check
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV_NCE_BAS401 Error & occurred while trying to free memory
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_NCE_BAS400 ** Error messages for function group CNV_NCEMAP (reserve up to no. 499 **
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_NCE_BAS403 Action cancelled
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_NCE_BAS404 All number range objects selected
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.