I get a database timeout expired error on my ASP.NET application.

 get the following error when my ASP.NET application connects to the MS SQL server:

System.InvalidOperationException: Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.

This error is caused by depleted database connections in the connection pool. To resolve the problem, you should

1) Check your application to make sure all database connections are closed when it is not needed. ASP.NET is supposed to have garbage collector to reclaim unused resource. However, on a busy site, it is likely that the connection pool will run out of connections before garbage collection kicks in.

2) You can raise the connection pool size in the connection string. For example, you can add "Max Pool Size=100" to your connection string to increase the pool size to 100.