It seems that the data is not imported properly on the new server.
I think your cms_page table in the database was missing its primary key values. Please check this table once. Some time if you export data from phpmyadmin it don't export all the data. You need to do it through command line to be sure that all data is exported properly. Use below command to export data.
mysqldump -u "username" -p "dbname" > abc.sql
enter password
To import through command line use
mysql -u "username" -p "dbname" < abc.sql
enter password.