Microsoft says Windows updates released since October 2026 Patch Tuesday can leave some SQL Server linked-server connections open after queries finish. Those connections can accumulate and degrade performance over time, according to November 12 reporting by BleepingComputer and The Register. SourceSource
The issue affects SQL Server linked-server queries that use OLE DB providers to retrieve data from external databases. Microsoft names Oracle and PostgreSQL connections among those known to be affected. SourceSource
Administrators might see an increasing number of open connections to external databases even when the associated linked-server queries are no longer running. The query is off the clock; its connection apparently isn't. SourceSource
Which Windows systems are affected?
The reports identify affected versions within Windows 10, Windows 11 and Windows Server 2012 and later. The Register's account specifically excludes Windows 11 26H2. SourceSource
Temporary relief comes with a catch
Microsoft says administrators who can identify idle connections may manually close them to temporarily reduce server load. Restarting the SQL service can also temporarily restore stability. Both measures can interrupt active queries or transactions, however, and the connection problem can return after further operation. That's a fairly large asterisk on the restart button. Source
As of the November 12, 2026 reports, Microsoft expected an out-of-band Windows update—outside the regular update schedule—within the next few days. In the meantime, the company said administrators could contact Microsoft Support for Business for an interim mitigation. The reports do not detail that mitigation's implementation or confirm that the update had shipped. SourceSource
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