Error when setting up database mirroring: “Create failed for Endpoint ‘Mirroring’. (Microsoft.SqlServer.Smo)”

When trying to set up database mirroring on SQL Server 2005, you may receive the following message:

Create failed for Endpoint 'Mirroring'. (Microsoft.SqlServer.Smo)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=9.00.1399.00&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.FailedOperationExceptionText&EvtID=Create+Endpoint&LinkId=20476

An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)

Database mirroring is disabled by default. Database mirroring is currently provided for evaluation purposes only and is not to be used in production environments. To enable database mirroring for evaluation purposes, use trace flag 1400 during startup. For more information about trace flags and startup options, see SQL Server Books Online. (Microsoft SQL Server, Error: 1498)

The solution is to enable mirroring by adding the trace flag 1400 to the startup parameters of the SQL Server service on both the primary and the mirror:

SQL Server Configuration Manager –> SQL Server Services –> Right click on SQL Server <instance name>, Go to properties, and click the "Advanced" tab.