Your MDS Excel Add-in Stopped Working. Here’s What Happened — and What to Use Instead.

The MDS Excel add-in stopped working in April 2025 because Microsoft disabled ActiveX controls by default in Office 365 (Build 2504+). The add-in depends on ActiveX to connect to Master Data Services, so when ActiveX was turned off, the add-in died. You can re-enable ActiveX via registry, but that's a temporary workaround against a vendor that has moved on. The real fix is a browser-based grid that doesn't need plugins at all.

You probably discovered this the hard way. You opened Excel, clicked the Master Data tab, and got a dialog box about ActiveX controls being disabled. You clicked OK, and the tab went dead. No connection to MDS. No data. The colleagues who'd been editing employee records and product codes through that add-in for years suddenly had nothing.

If this happened to your team, you were not alone. According to Microsoft's own documentation, the ActiveX change affected all Microsoft 365 Win32 apps across Current Channel, Monthly Enterprise Channel, and Semi-Annual Enterprise Channel. Every organization running MDS with the Excel add-in on Office 365 was impacted. Here's what actually broke, why the fixes being shared online are temporary, and what a permanent replacement looks like.

What actually happened in April 2025

Microsoft had been signaling this for years. ActiveX controls — the technology that powers the MDS Excel add-in — are a legacy framework from the Internet Explorer era. They run executable code inside documents. In modern security terms, that's a liability Microsoft no longer wanted to carry.

Starting with Office 365 Build 2504 (April 2025), ActiveX controls are disabled by default in all Microsoft 365 apps. No opt-in, no warning banner — they just stopped loading. The MDS Excel add-in relies on ActiveX for its connection panel, model browser, and entity publishing controls. Without ActiveX, the entire add-in is inert.

Technical detail: The change was announced via the Microsoft 365 Insider Blog. The registry key HKCU\Software\Microsoft\Office\Common\Security\DisableAllActiveX was set to 1 by default. You can reverse it, but Microsoft's documentation explicitly discourages it for security reasons.

The registry workaround is duct tape

Yes, you can re-enable ActiveX. Forums are full of the fix: set the registry key to 0, or push it via Group Policy. Your MDS add-in comes back. Problem solved. Except for three things.

First, you're fighting Microsoft's direction. They disabled ActiveX for security reasons, and they're not going to reverse that. The next Office update might break your override again. Your security team will keep flagging the registry exception. And the longer you maintain this workaround, the less time you have to actually migrate before MDS itself disappears.

Second, MDS itself is deprecated. Even if you get the add-in working today, MDS is gone in SQL Server 2025. The product has no roadmap, no new features, and an explicit end-of-life. Re-enabling the add-in keeps a dying product alive for a few more months.

Third — and this is the one nobody talks about — the MDS Excel add-in was never good. It was the least bad option for getting non-technical users into MDS without the Silverlight web UI, which was worse. But it had real limitations that teams simply learned to live with.

What the add-in couldn't do (even when it worked)

The MDS Excel add-in gave your data stewards a spreadsheet-like view of entity data. That sounds fine until you think about what a master data editing interface actually needs.

What a replacement actually needs to do

The MDS Excel add-in was popular for one reason: data stewards didn't want to learn a new tool. Excel was familiar. Filtering, sorting, copy-pasting — they already knew how. Any replacement that forces them into a radically different workflow will face the same adoption problem MDS's Silverlight UI had.

The answer isn't “Excel in the cloud” or another add-in. It's a browser-based grid that feels like a spreadsheet but behaves like a proper data management tool. Click a cell, type, done. No “Publish” button. No version conflicts. No ActiveX.

The grid needs to support the things Excel couldn't: domain dropdowns that filter based on parent values (so you don't show 200 departments when only 12 belong to the selected branch), per-row audit trails visible on click, and an approval workflow that doesn't require users to understand what a changeset is.

And it needs to run on SQL Server. Not beside it. Not in Azure with a sync connector. On the same database your team already manages. The whole point of MDS was that master data lived in your SQL Server instance. That shouldn't change just because the UI does.

How Primentra replaces the MDS Excel add-in

Primentra is a browser-based master data management tool that runs on your SQL Server. There's no Excel add-in, no ActiveX, no COM registration, and nothing for Microsoft to disable in a future update.

Data stewards open a URL, see their entities in a grid, and start editing. Click a cell, type the new value — it saves automatically. Filter, sort, paste from clipboard, add rows, delete rows. The keyboard shortcuts are the same ones they already know from Excel: Tab to move right, Enter to move down, Ctrl+C/V to copy and paste. The learning curve is measured in minutes, not weeks.

The stuff the Excel add-in couldn't do is where it gets interesting. Every edit is logged with who changed it, when, and what the old value was. Domain dropdowns actually filter based on parent values, so your data stewards see 12 relevant departments instead of all 200. And the approval workflow is straightforward: submit changes, someone approves or rejects them, done. No changesets, no staging tables to babysit. We wrote more about the cascading dropdown filters in a separate post.

If you're migrating from MDS, the migration wizard brings your models, entities, and attributes over. Your data stays in SQL Server. Your DBAs can still query the tables directly. Nothing moves to the cloud unless you want it to.

Frequently asked questions