Error upgrading gitlab from 6.0.2 to 7.14 on UI Gitlab page loads to 500 page

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 182.74.39.146 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 projects.id FROM projects INNER JOIN namespaces ON projects.namespace_id = namespaces.id INNER JOIN users_groups ON namespaces.id = users_groups.group_id WHERE namespaces.type IN (‘Group’) AND users_groups.user_id = 161):
app/models/user.rb:245:in authorized_projects’
app/controllers/dashboard_controller.rb:67:inload_projects’