getting this error in ms sql sever The backend version is not supported to design database diagrams or tables.

Solution:

Database was designed in new version, and if user tried to add new table or any new database diagram. then you will get
error message "The backend version is not supported to design database diagrams or tables."

run below sql script "Query window" editor. you can see in which version of ms sql server, database was designed

select @@version