User permission error when accessing "user instance" database from ASP.NET

Question

The server hosting csharpindepth.com has recently been migrated.

Most of it is working fine, but I can't get at the database used to hold errata, notes etc.

Relevant details:

• 32 bit Windows Server 2003
• SQL Server Express 2005 installed
• ASP.NET pool running under "NETWORK SERVICE" account
• .NET 3.5
• Everyone has full permission to database files (at the moment, just to rule that out!)

• Connection string:

  Data Source=.;AttachDbFilename=|DataDirectory|\WebSiteData.mdf;
  Integrated Security=True;User Instance=True
  

• I'm connecting just by creating a new WebSiteDataContext (which has the above connection string as its default)

Using a small test console app running from the directory containing the files, as the administrator account, using the same query, I can see the contents of the database.

In ASP.NET I'm getting this exception:

SqlException (0x80131904): User does not have permission to perform this action.

EDIT: More information, here's the stack trace:

[SqlException (0x80131904): User does not have permission to perform this action.]
   System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +4844759
   System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) +194
   System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) +2392
   System.Data.SqlClient.SqlInternalConnectionTds.CompleteLogin(Boolean enlistOK) +35
   System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject) +144
   System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart) +342
   System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) +221
   System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) +189
   System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) +4859187
   System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) +31
   System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject) +433
   System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject) +66
   System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +499
   System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +65
   System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +117
   System.Data.SqlClient.SqlConnection.Open() +122
   System.Data.Linq.SqlClient.SqlConnectionManager.UseConnection(IConnectionUser user) +44
   System.Data.Linq.SqlClient.SqlProvider.get_IsSqlCe() +45
   System.Data.Linq.SqlClient.SqlProvider.InitializeProviderMode() +20
   System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query) +57
   System.Data.Linq.DataQuery`1.System.Collections.Generic.IEnumerable<T>.GetEnumerator() +35

EDIT: I was wrong about the filename having to be right - changing the connection string to make it talk to a different file doesn't change the error.

ProcMon never shows it touching the file...

EDIT: Further oddities - restarting the application pool with it running under the Local System account still has problems, which is about as odd as it gets! It's as if, despite the error message, it's actually trying to do something impossible (e.g. with the wrong path) rather than just being a permissions issue.

EDIT: More information - I've just run my little test console app from a service as "NETWORK SERVICE" and (after an initial attempt which timed out) it was successful. So it's not a permissions thing in terms of the user account... it's something about the environment in which it runs...

Answer 1

Does the child instance even start? When a RANU database is requested the master instance (.\SQLEXPRESS in this case) has to create a 'child' instance, in other words start the sqlservr.exe process as an user process running under the credentials of the user that requested the RANU connection from the .SQLEXPRESS instance. In this case the instance would have to be started as 'NETWORK SERVICE'.

To validate if the child instance is started, connect to the master instance (.\SQLEXPRESS) and check sys.dm_os_child_instances:

SELECT * 
FROM sys.dm_os_child_instances

If an NETWORK SERVICE owned child instance is started, take it's instance_pipe_name and connect straight to the child instance:

sqlcmd -S np:\\.\pipe\<child pipe name>\tsql\query

Ideally, connect as NETWORK SERVICE (eg. from an interactive cmd console started as NEWTORK SERVICE, perhaps using at.exe to schedule it 1 minute in future). If that works, the last step is to try to attach the MDF using ordinarry sp_attach_db.

The idea of these steps is not to solve the issue, but pinpoint the failure cause, since the error you get is kinda generic and ... not exactly helpfull.