Download Microsoft Jet Oledb 4.0 [verified] Page
This is the most critical step. Do not change your provider without updating your code.
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.
If you must run your application in a 64-bit environment, you cannot use Jet OLEDB 4.0. You must download its modern successor, the . The ACE provider supports both .mdb and newer .accdb file formats and is available in native 64-bit versions. Where to Download Modern Jet Alternatives
If your environment must remain completely 64-bit, you must migrate away from Jet. download microsoft jet oledb 4.0
Recompile and run the application. This forces the program to run as a 32-bit process, allowing it to successfully communicate with Jet 4.0. Solution B: Configure IIS for 32-Bit (For Web Developers)
For modern applications, particularly those requiring 64-bit support or compatibility with newer Office file formats ( .accdb ), Microsoft has superseded Jet with the .
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The official Microsoft recommendation is to download and install the (or a later version, such as the 2016 version). This redistributable package is designed to provide the necessary drivers for 64-bit systems and includes the Microsoft.ACE.OLEDB.12.0 provider, which is the direct replacement for Microsoft.Jet.OLEDB.4.0.
If you have landed on this page searching for the phrase you are likely a developer, a database administrator, or an IT professional trying to connect an application to a legacy Microsoft Access database ( .mdb ) or an Excel spreadsheet. You might be wrestling with error messages like "The 'Microsoft.Jet.OLEDB.4.0' provider is not registered on the local machine" or "Unrecognized database format."
Fix 1: Change IIS Application Pool Settings (For Web Developers) Open the . Click on Application Pools in the left sidebar. Select the application pool running your website. Click Advanced Settings in the right sidebar. Find Enable 32-Bit Applications and change it to True . Click OK and recycle the application pool. It is deprecated, unmaintained, and has known security
Many old guides suggest MDAC 2.8. MDAC does not contain Jet OLEDB – only SQL Server, Oracle, etc.
To force the installation of the 32-bit engine alongside 64-bit Office:
Open Command Prompt (Admin) and run:
Before you click on a sketchy "download now" button from a third-party website, you need to understand a critical piece of Windows history. Here is everything you need to know—what it is, why it is missing, how to get it, and the modern alternatives.