Dear Chinna,
As replied to your colleague Praneeth, on the same topic pls perform the below:
The custom Y/Z structure YMARA was deleted in your system by someone, but the corresponding APPEND of YMARA wasn't deleted from the standard structure WPMARA. So you are getting the error.
Solution:
1. Either re-create structure YMARA in DDIC
2. Delete the append structure from the standard structure WPMARA
Thanks,
Sanjay