Windows 11 KB5066835 is causing the following issues: a bug that blocks lockhost connection, File Explorer preview pane and ...

Microsoft has fixed a known issue breaking HTTP/2 localhost (127.0.0.1) connections and IIS websites after installing recent Windows security updates.

Update 10/17/25: Microsoft fixes the bug using a KIR (Known Issue Rollback) update. More information added to end of story. Microsoft's October Windows 11 updates have broken the "localhost" ...