SQL Server Slowing Down After Windows Updates? Check Your Linked Servers.

SQL Server getting slower after recent Windows updates? Before chasing execution plans, missing indexes, or memory pressure, take a look at your linked servers.

On November 11, 2026, Microsoft confirmed an issue with Windows updates released October 13 and later. According to the Windows release health dashboard:

"Connections created by SQL Server linked server queries might remain open after the queries complete."

Those connections can accumulate over time, degrading performance and stability. The longer the server runs, the worse it can get.

What's Happening?

The reported issue affects SQL Server linked server queries using OLE DB providers to access external databases. Oracle and PostgreSQL are among the confirmed targets.

The query completes but the connection may not always close. Repeat that often enough, and the external database can end up with a growing collection of open connections that no longer have active SQL Server queries behind them.

That distinction matters. This is not a blanket claim that the Windows updates slow every SQL Server workload. The confirmed issue concerns linked-server connections to external databases - and it will impact performance.

What Should DBAs Check?

• Patch history: Were Windows updates installed shortly before the slowdown began?
• Linked servers: Does the instance query external databases through OLE DB providers, particularly Oracle or PostgreSQL?
• Connection counts: On the external database, are open connections increasing even after the corresponding linked server queries have completed?
• Trend: Does performance worsen over time rather than immediately after the server starts?

Not sure which linked servers are configured? This quick query will tell you what you've got:

SELECT
    name,
    product,
    provider,
    data_source
FROM sys.servers
WHERE is_linked = 1
ORDER BY provider, name;

Pay particular attention to Oracle and PostgreSQL, but don't rule out other external databases.

What About a Fix?

As of November 12, Microsoft says an out-of-band Windows update is planned for the coming days. The fix has not yet been released.

Microsoft says administrators may be able to manually close the leftover connections or restart the SQL Server service for temporary relief. But a restart interrupts active work, and the issue can return. Neither is a permanent solution.

For environments already affected, Microsoft recommends contacting Microsoft Support for Business about an interim mitigation.

One More Linked Server Surprise

Earlier this year, we had the MSDASQL error 7416 issue, where certain linked-server queries failed after SQL Server updates. I wrote about that here. That was a different problem, involving connection validation. This one is about connections that can remain open after a query finishes.

Different symptoms. Same lesson: when SQL Server starts behaving strangely after patching, be sure to check your linked servers.

More to Read

Microsoft - Windows Server 2022 release health: SQL Server linked server connections
sqlfingers - When a Security Patch Breaks Your Linked Servers
BleepingComputer - Microsoft confirms Windows update-related SQL Server performance issues