Upgrading multilingual site causes DB Error
Upgrading from CiviCRM 4.4.7 to 5.4.0 (Drupal), cause a DB error. Upgrade process works fine but when loading any civi page, JavaScript error is displayed on the language file (backtrace displayed after enabling).
Checking the error log, few fields relating to uf_group are not getting created during the upgrade.
Further investigation showed that in CRM/Core/I18n, there have been schema changes between the latest SchemaStructure.php and SchemaStructure_4_7_alpha1.php thus we had to copy and rename the file as SchemaStructure_5_4_alpha1.php as mentioned here.