Potential causes of the "SQL Server does not exist or access denied" error message
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Applies to: Microsoft SQL Server 2000 Standard EditionMicrosoft SQL Server 7.0 Standard EditionMicrosoft SQL Server 2005 Standard EditionMicrosoft SQL Server 2005 Express EditionMicrosoft SQL Server 2005 Developer EditionMicrosoft SQL Server 2005 Enterprise EditionMicrosoft SQL Server 2005 Workgroup EditionMore
Extended support for SQL Server 2005 ended on April 12, 2016
"SQL Server does not exist or access denied" is a generic Microsoft Data Access Components (MDAC) message that indicates that the computer that is running Microsoft SQL Server cannot be contacted. This generic message has many potential causes.
Additionally, the following error messages also have similar causes:
SQL Server is unavailable or does not exist.
The specified SQL Server is not found.
Important The "SQL Server does not exist or access denied" message does not indicate the following:
The logon process to SQL Server failed.
SQL Server does not have the correct permissions to process the query.
You cannot use SQL Server authentication because only Windows authentication is permitted.
You are using "LocalHost" in an ADO connection string. This is not supported; use "(local)" or the computer name instead. Per "SOX001027700080 SQL INF Server - Connectivity: Using LocalHost" this is not supported and it may or may not work. However, some "How To" articles use LocalHost in their examples.