> For the complete documentation index, see [llms.txt](https://docs.os.uk/os-downloads/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.os.uk/os-downloads/products/buildings-and-infrastructure-portfolio/os-mastermap-topography-layer-building-height-attribute/os-mastermap-topography-layer-building-height-attribute-known-data-issues.md).

# OS MasterMap Topography Layer – Building Height Attribute Known Data Issues

This page provides the details of known data issues in the OS MasterMap Topography Layer – Building Height Attribute product. Once resolved, details will be held until the next release of the product.

## Live known data issues

| Data Issue                                                                                                              | Description Issue Description and Update                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| ----------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Corruption affecting seven tiles in the April 2025 release of OS MasterMap Topography Layer – Building Height Attribute | <p>An issue has been identified with the below files in the April 2025 release of the product:</p><p><em><strong>NO0005.csv</strong></em><br><em><strong>NO7075.csv</strong></em><br><em><strong>NX6590.csv</strong></em><br><em><strong>NZ9505.csv</strong></em><br><em><strong>SE5080.csv</strong></em><br><em><strong>SP5545.csv</strong></em></p><p><em><strong>NT2065.csv</strong></em></p><p>These files have now been replaced for any new order submissions. However, if you received an April 2025 update order containing these files or accessed the data between 01 and 10 April 2025, you may encounter an issue in loading these files.</p><p>To resolve this, the files can be reordered or resupplied on request.</p><p>We apologise for any inconvenience caused and appreciate your understanding and cooperation.</p> |

{% hint style="info" %}
To report an issue not currently listed here, please visit the ['Contact us' page on the OS website](https://www.ordnancesurvey.co.uk/contact-us/business-government/use-os-data).
{% endhint %}


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