OS MasterMap Topography Layer Known Data Issues and Service Disruptions

This page provides the details of known data issues and service disruptions impacting the OS MasterMap Topography Layer product.

Live known data issues and service disruptions

There are no live known data issues for OS MasterMap Topography Layer at this time.

Resolved data issues

Data Issue	Original Data Issue Description	Data Issue Resolution Date	Resolution Message
Delay to OS MasterMap Topography Layer product refresh	Between 01 and 03 September 2025, there was a delay in publishing the latest release of the OS MasterMap Topography layer.	03/09/2025	We are pleased to confirm that the delay to publishing the 1 September release of the OS MasterMap Topography Layer has now been resolved. The product was successfully published on 3 September 2025. We apologise for any inconvenience this may have caused.
Incorrect query extent coordinates in GML Geo chunk header file (orders 08 to 21 August 2025)	Between 08 and 21 August 2025, geographically chunked orders of OS MasterMap Topography Layer contained incorrectly formatted coordinates in the query extent header file for specific 100km² tiles. This may cause processing issues in software that relies on the query extent, such as certain versions of FME with specific transformers which have generated errors in the log files. GoLoader- and Python-based solutions have not encountered an issue. Impacted 100km² tiles: SV, SW, SX, SY, SZ, TV, NL, NF, NA, HW, HX, HY, HZ, HT, HU, HP and tiles along the edges of ND and HY. A visual representation of the 100km² tiles regions can be found here: BritishNationalGrid.uk.	21/08/2025	A fix has been implemented for all new orders from 21 August 2025 onwards. Customers with non-geographical chunked orders will not be impacted by the issue. If you experience any issues, then please contact the Fulfilment Team at [email protected] who will be able to provide you with a resupply.
Broken download links for OS MasterMap Topography Layer GML 5km tile download orders	Customer topography 5x5km tile download orders supplied from 30 July 2025 to 12 August 2025 contain broken download links. As a result, an error message will be displayed saying there is no data available to download.	12/08/2025	This issue was fixed on 12 August 2025 and new orders after this date will not be impacted. Any impacted customers will be contacted directly and we aim to resupply any impacted orders by 15 August 2025.
Missing FVDS file in the OS MasterMap Topography Layer (GML Non Geo chunk 30MB) Managed GB Set supplied on 28 April 2025	An issue has been identified with the recent OS MasterMap Topography Layer (GML Non-Geo chunk 30MB) Managed GB Set update order supplied on 28 April 2025. Unfortunately, the FVDS file was missing from the original order.	01/05/2025	To address this issue, we have resupplied affected customers with a new update order containing the missing FVDS file. A notification email with instructions on how to download this new order has been sent out. Please disregard the initial order. The issue resulted from a manual user error, and we are working on solutions to prevent this happening in the future. We apologise for any inconvenience this may have caused and appreciate your understanding.

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