https://userapps.support.sap.com/sap/support/knowledge/en/1867073
1867073 - Message TK430 is issued in T-code: OKOG in a production system | SAP Knowledge Base...
Message TK430 is issued when you try to make change in T-code: OKOG in a production system. Thus you can not make any changes in T-code:OKOG.
https://userapps.support.sap.com/sap/support/knowledge/en/2827232
2827232 - OKEW TK430 | SAP Knowledge Base Article
When running OKEW, there's message TK430.
sap knowledgebasearticle
https://userapps.support.sap.com/sap/support/knowledge/en/2409759
2409759 - Error message TK430 when running PT02 | SAP Knowledge Base Article
Message TK430: (Client XXX has status 'not modifiable') pops up by running transaction PT02.
error messagesap knowledge
https://userapps.support.sap.com/sap/support/knowledge/en/3561627
3561627 - Error TK430 occurs when execute Tcode KP34 | SAP Knowledge Base Article
Error TK430 (Client XXX has status 'not modifiable')is issued in T-code KP34.