Internet Information Server (IIS), by default, uses an apartment-threaded, or single-threaded, threading model. This design choice was made because many Web sites still used Access as the database backend. Access, being a desktop database system, was not designed to work with multiple concurrent users. As you migrate your databases to SQL Server, you should change the threading model to free-threaded, or multithreaded, to take advantage of SQL Server. To change the threading model, run “makfre15.bat” from C:Program FilesCommon FilesSystemado. If you need to revert back to apartment threading later, run “makapt15.bat”.