Gitlab page loads to 500 page after upgrade

Gitlab page loads to 500 after its upgraded from 6.0.2 to 7.14.

Error found in the production.log is as follows :
Started GET “/” for at 2017-10-31 12:44:42 +0100
Processing by DashboardController#show as HTML
Completed 500 Internal Server Error in 383ms

ActiveRecord::StatementInvalid (Mysql2::Error: Table ‘gitlabhq_production.users_groups’ doesn’t exist: SELECT FROM projects INNER JOIN namespaces ON projects.namespace_id = INNER JOIN users_groups ON = users_groups.group_id WHERE namespaces.type IN (‘Group’) AND users_groups.user_id = 161):
app/models/user.rb:245:in authorized_projects’