Download Microsoft Jet Oledb 4.0 < 2024 >
Let us say your legacy VB script has:
Set conn = CreateObject("ADODB.Connection")
conn.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\data\old.mdb"
To modernize:
Install it. Run the downloaded .exe as Administrator. download microsoft jet oledb 4.0
Modify your connection string:
Change Jet.OLEDB.4.0 to ACE.OLEDB.12.0 (or 16.0).
conn.Open "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\data\old.mdb"
Test. Your old .mdb file should open seamlessly. If you get "Unrecognized database format," ensure you installed the correct bitness. Let us say your legacy VB script has:
If you are starting a new project or have the ability to refactor, Microsoft strongly advises against using Jet OLEDB 4.0. It is deprecated, unmaintained, and has known security vulnerabilities.
| Alternative | Best For | Provider String / Method |
| --- | --- | --- |
| Microsoft.ACE.OLEDB.12.0 (or 16.0) | Modern Access (.accdb) and Excel files. Supports both 32-bit and 64-bit. | Provider=Microsoft.ACE.OLEDB.12.0;Data Source=... |
| System.Data.Odbc | Bridge to modern Access drivers. | Use ODBC instead of OLEDB. |
| SQLite | Moving small database files into a modern, supported engine. | Migrate your .mdb tables to SQLite. |
| SQL Server Express | Scalable, secure, networked database solution. | Use SqlConnection instead of OleDbConnection. | To modernize:
Unlike the later Microsoft Access Database Engine 2010/2016 Redistributable, Jet 4.0 was never packaged as a standalone installer you could legally distribute. Any website offering Jet40SP8_9xNT.exe or similar is likely an old archive—not a supported Microsoft download.
Microsoft replaced Jet 4.0 with the Microsoft Access Database Engine. This allows you to interact with Access databases (and Excel files) using modern systems.