How To Fix DD_DBAL027 - Table &1: Alter type into table type &2 not allowed

SAP Error Message - Details

• Message type: E = Error

• Message class: DD_DBAL - ABAP Dictionary, Data Base Abstraction Layer

• Message number: 027

• Message text: Table &1: Alter type into table type &2 not allowed

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message DD_DBAL027 - Table &1: Alter type into table type &2 not allowed ?

  The SAP error message DD_DBAL027 indicates that there is an issue with altering the type of a table in the database. Specifically, the error message states: "Table &1: Alter type into table type &2 not allowed." This typically occurs when there is an attempt to change the structure or type of a database table that is not permitted due to various constraints.
  Cause:
  
  Incompatible Data Types: The error often arises when there is an attempt to change the data type of a field in a table that is not compatible with the existing data or structure.
  Table Type Restrictions: Certain table types (like transparent tables, pooled tables, etc.) have restrictions on how they can be altered. For example, you cannot change a transparent table to a pooled table or vice versa.
  Foreign Key Constraints: If the table has foreign key relationships, altering the type may violate those constraints.
  Data Dictionary Restrictions: The SAP Data Dictionary has specific rules regarding how and when tables can be altered.
  
  Solution:
  
  Check Data Types: Review the data types of the fields in the table and ensure that the new type you are trying to apply is compatible with the existing data.
  Use the Correct Table Type: Ensure that you are not trying to change the table type in a way that is not allowed. If you need to change the structure, consider creating a new table with the desired structure and migrating the data.
  Remove Constraints: If there are foreign key constraints or other dependencies, you may need to temporarily remove them before making the changes and then re-establish them afterward.
  Use Transaction SE11: Use transaction SE11 (Data Dictionary) to check the table definition and make the necessary adjustments. You can also use the "Technical Settings" to see if there are any restrictions.
  Consult Documentation: Refer to SAP documentation or notes related to the specific version you are using for any additional guidelines or restrictions regarding table alterations.
  
  Related Information:
  
  Transaction Codes: SE11 (Data Dictionary), SE14 (Database Utility), SE37 (Function Module), SE80 (Object Navigator).
  SAP Notes: Check for any relevant SAP Notes that might address this specific error or provide additional context.
  Backup Data: Always ensure that you have a backup of your data before making structural changes to database tables.
  
  If the issue persists after trying the above solutions, it may be beneficial to consult with an SAP Basis or ABAP consultant who can provide more tailored assistance based on your specific system configuration and requirements.