AddressBase Core Data Issues, Service Disruptions and Planned Maintenance

This page provides the details of known data issues and service disruptions impacting the AddressBase Core product. It also provides information on any planned maintenance periods.

Live known data issues

There are no live known data issues for AddressBase Core at this time.

To report an issue not currently listed here, please visit the 'Contact us' page on the OS website.

Resolved data issues

Incorrect GSS code values for address records in Sheffield and Barnsley

The AddressBase Core product refresh scheduled for the week commencing 11 August 2025 only contained changes to correct the GSS (Government Statistical Service) codes for Sheffield and Barnsley. Changes from Local Authorities, Royal Mail or Ordnance Survey were not available in that week's product refresh.

The AddressBase Core product refresh scheduled for the week commencing 19 August 2025 successfully included two weeks’ worth of change from Local Authorities, Royal Mail and Ordnance Survey.

Data Issue Description

Last Update

An issue was encountered following the change in GSS codes for Sheffield and Barnsley that took effect on 01 April 2025. This has resulted in AddressBase Core currently displaying the historic GSS code. The previous and current GSS code changes as of 01 April 2025 are detailed in the table below: Local Authority District Current AB Core (historic) GSS Code Correct GSS Code (Effective from 01 April 2025) Barnsley E08000016 E08000038 Sheffield E08000019 E08000039

GSS code fix planned for the week commencing 11 August 2025, with full implementation during the week commencing 19 August 2025. 10/06/2025 – Under investigation 12/08/2025 – Fix successfully implemented and released week commencing 11/08/2025. 19/08/2025 – This week's release contained all previously suspended updates.

Service disruption

There are no live service disruptions affecting AddressBase Core at this time.

Planned maintenance

No maintenance events are currently scheduled that will impact the availability of AddressBase Core.

Maintenance previously planned for the week commencing 24 November 2025 was completed early

Please note that maintenance event scheduled to take place from Monday 24 November to Sunday 30th November 2025 has been completed ahead of schedule and will no longer need to take place. Customers who receive Change-Only Update (COU) orders will receive their weekly COU file as usual as there will be no blank files in this refresh.