How To Fix CME_DTYPE020 - You cannot change the data type

SAP Error Message - Details

• Message type: E = Error

• Message class: CME_DTYPE - CME Data Type: Checks

• Message number: 020

• Message text: You cannot change the data type

What causes this issue?

The data type has versions - higher versions must remain compatible
with lower versions.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message CME_DTYPE020 - You cannot change the data type ?

  The SAP error message CME_DTYPE020, which states "You cannot change the data type," typically occurs when you attempt to modify the data type of a field in a database table or structure that is not allowed due to various constraints. This error is often encountered in the context of ABAP Dictionary (SE11) or when working with data elements and domains.
  Causes:
  
  Existing Data: If there is existing data in the database table that is incompatible with the new data type, SAP will prevent the change to avoid data loss or corruption.
  Dependencies: The field may be used in other database objects, such as views, indexes, or foreign key relationships, which restricts changes to its data type.
  Data Element Restrictions: If the field is based on a data element that has been defined with specific attributes, changing the data type may violate those definitions.
  Transport Requests: If the object is part of a transport request that is already in process, changes may be restricted.
  
  Solutions:
  
  Check Dependencies: Before changing the data type, check for any dependencies on the field. You can use transaction SE11 to analyze where the field is used and ensure that changing the data type will not affect other objects.
  Data Migration: If you need to change the data type, consider creating a new field with the desired data type and migrating the data from the old field to the new one. This can be done using ABAP programs or data migration tools.
  Adjust Data Type: If the change is necessary, you may need to drop or modify dependent objects (like views or indexes) before changing the data type. Ensure that you have a backup and that you understand the implications of these changes.
  Consult Documentation: Review SAP documentation or consult with your SAP Basis or ABAP team for best practices on changing data types.
  Use a New Data Element: If the data type change is significant, consider creating a new data element with the desired data type and using it in your table or structure instead of modifying the existing one.
  
  Related Information:
  
  Transaction Codes: SE11 (Data Dictionary), SE14 (Database Utility), SE37 (Function Builder) for checking function modules that might be using the field.
  SAP Notes: Check SAP Notes for any specific guidance or known issues related to this error message.
  Testing: Always test changes in a development or quality assurance environment before applying them to production to avoid unintended consequences.
  
  If you continue to face issues or if the situation is complex, it may be beneficial to consult with an SAP expert or your organization's SAP support team for tailored assistance.