SQL Server 2022 CU26 breaks Master Data Services
If you patched SQL Server 2022 to cumulative update 26 and your Master Data Services web application now opens to an empty screen, you are not alone.
What happens
Section titled “What happens”Administrators have reported that after installing SQL Server 2022 CU26 (build 16.0.4265.3), the MDS web application loads, but shows no models, no entities and no data. The MDS database is intact. Everything is still there and visible through the SQL views and tables. It is the web layer that no longer works.
Uninstalling CU26 does not fix it. The MDS assemblies in Master Data Services\WebApplication\bin stay at the new version even after the update is rolled back.
The workaround
Section titled “The workaround”Administrators have reported that replacing the files in WebApplication\bin with the versions from before CU26 brings the web application back. This is a workaround, not a fix. It leaves you on a mix of file versions, and it has to be repeated if the assemblies are updated again.
The problem and the workaround are described in a thread on Microsoft Q&A, where a moderator recommended opening a support case with Microsoft. CU27, released on 15 September 2026, does not list a fix. Instead, its list of known issues says that some Master Data Services features might not work as expected, including creating entities and attributes and loading hierarchies in Explorer, and that Microsoft is investigating a fix.
What it means
Section titled “What it means”MDS is removed in SQL Server 2025. Microsoft continues to support it on SQL Server 2022 and earlier, but the direction is clear. CU26 is a reminder that “supported” and “maintained” are not the same thing. A component that is on its way out will not get the same attention when something breaks.
If your organisation uses MDS for account mappings, reporting hierarchies, limits or parameters, the practical question is not whether to move, but when and to what.
Where Grunddata fits
Section titled “Where Grunddata fits”Grunddata is built for the data most organisations keep in MDS. The data the business owns and everyone else reads.
The mapping is direct. An MDS model becomes a Grunddata model. An entity becomes a table. Attributes and domain-based attributes carry over. Subscription views become Grunddata views, exposed through OData so Power BI and the data warehouse keep reading from the same place.
What you gain is a system with a future. MDS was an on-premise product tied to SQL Server. Grunddata is a cloud service in a dedicated EU environment, with Microsoft Entra ID for sign-in. Your data is available through API, OData and MCP. Every save is a commit with author, timestamp and message, and the business keeps working in Excel through the add-in.
What to do now
Section titled “What to do now”- Test CU26 and CU27 on a non-production MDS server before you install them in production, and hold off in production until Microsoft confirms a fix.
- If you already have, apply the bin-file workaround and take a backup of the MDS database before you touch anything.
- Read our guide on migrating from Microsoft Master Data Services. It covers what MDS is typically used for, what your options are, and how a move to Grunddata works in practice.
If you want a second opinion on your setup, get in touch. We have seen this exact situation at a customer and can walk you through it.