Windows updates since October 2026 cause SQL Server slowdowns, Microsoft confirms
Administrators running linked server queries through OLE DB providers face building connection leaks until Microsoft ships an out-of-band fix.
Microsoft has acknowledged that Windows updates shipped after the October 2026 Patch Tuesday are triggering SQL Server slowdowns and instability. The root cause is that linked server queries using OLE DB providers leave their connections to external databases open once they finish, so those connections pile up and erode server performance over time. Oracle and PostgreSQL links are among the affected cases, and the problem affects both Windows 10 and 11 clients as well as Windows Server 2012 and later. Restarting the SQL service or closing the stray connections offers only temporary relief, since the symptoms return later and a restart can terminate running queries. Microsoft plans to ship an out-of-band Windows update within days and says administrators can contact Microsoft Support for Business for an interim mitigation.
Why it matters
The fault sits in the connection handling of linked server queries, so any organisation whose SQL Server reaches external databases such as Oracle or PostgreSQL is exposed, whether on Windows 10 and 11 clients or Windows Server 2012 and later. A restart gives only short relief, and because it can end running queries, the cost of the workaround falls on the people whose work is interrupted. The coming out-of-band update is the real resolution, and until it arrives the problem is persistent rather than a one-off.
Matters or hype?
Does this story matter, or is it hype? Vote before you see what everyone else said.