MS Access Connection在本地工作，但在生产环境中不工作

Question

As a MVC developer I am creating an application for a school, I have a MS Access db and it is located inside my application, in the app_data folder. I created the connection string in the web.config file like below

<add name="WMOERP1" connectionString="Provider=Microsoft.Jet.OLEDB.4.0;Data Source='|DataDirectory|\Register.mdb'" providerName="System.Data.OleDb" />

It works perfectly in my local system but when I uploaded it in production I got the error

The 'Microsoft.ACE.OLEDB.12.0' provider is not registered on the local machine

Please help me how can I solve this I also tried to change the connection string below you can see that but still having the issue

<add name="WMOERP1" connectionString="Provider=Microsoft.ACE.OLEDB.12.0;Data Source='|DataDirectory|\Register.mdb'" providerName="System.Data.OleDb" />

Please help me .

Answer 1

An application that uses the Microsoft.JET.OLEDB.4.0 is an application that runs in 32bit mode. Thus you have set your project properties to target the x86 CPU platform or you have set the AnyCPU target platform with the Prefer 32bit flag.

In any case, when you deploy your application on IIS server 64 bit you should inform IIS that you want to run a 32bit application.

This is done going to the IIS configurator, choose Application Pools, create or highlight the application pool where you app will run and, on the right click menu, choose the Advanced Settings menu. From there set the Enable 32 bit application flag to true. Restart everything.

Here a description of the process with a step by step images

Of course you could keep your original Microsoft.Jet.OLEDB.4.0 connection string because this library is deployed with the NET Framework libraries and you don't need to do anything.
Instead to change to ACE.12.0 you need to install the libraries and, being your application a 32bit one, you need to install the 32bit version of ACE. The error seems to indicate that you have installed the 64bit version and thus there is no ACE.12.0 for 32bit apps (And no, you can't install both ACEs on the same machine)