Symptoms: 

Translate an IDML file. In BWB, delete a placeholder or change its order. Save the target file and you will see the following error:

"System.NotImplementedException: The method or operation is not implemented."

The previous error message did not indicate exactly which segment has problems. It has been replaced with a more specific message which points to the exact segment that causes the error.

Resolution: 

You can fix this issue by deploying the update to WorldServer 10.4.5, available on FTP.

If you cannot deploy it, contact the SDL Support Team:

•     Log on to your "My SDL" Account.
•     Log a support request via Support & Education Support. 

Notes: 

• All systems running WorldServer 10.4.5 should have this hotfix applied.
• The fix for this issue is also available in WS 11.1.1.