If you are getting an error like the one below in your ASP.Net application when trying to open an Excel or Access file, you may need to reset IIS.
System.Data.OleDb.OleDbException: Unspecified error
at System.Data.OleDb.OleDbConnectionInternal..ctor(OleDbConnectionString constr, OleDbConnection connection) at System.Data.OleDb.OleDbConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningObject) at System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection(DbConnection owningConnection, DbConnectionPoolGroup poolGroup) at System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) at System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) at System.Data.OleDb.OleDbConnection.Open() at
To reset IIS:
- Open a command prompt on the box running IIS.
- Issue the command: iisreset
My situation was that I had code that had previously worked, but it just stopped working one day with the error mentioned above.
Hope this helps.
David is an IT professional with over 26 years of experience (he started his career as a teenager). He has programmed in more languages and on more types of computers (and similar devices) than he can remember, including TRS-80 Model I Level 2, Commodore Vic-20 and C-64, C-128, Industrial Process Controllers, CP/M machines, and Intel 80x86+ architectures. He currently uses Microsoft .NET Framework tools and SQL Server.
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He lives in Charlotte NC, USA. 
Windows Update might have some security change.
Can you let me know which settings have been changed? strange only 2 of 50 websites have this problem, >> before no problem