Q:

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

I'm trying to get data from an Excel file on a button click event. My connection string is:
 string connString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\source\\SiteCore65\\Individual-Data.xls;Extended Properties=Excel 8.0;";

When I click on the button, I got the following error:

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

I have no clue how to fix this. My operating system is Windows 7.

A:

Well, you need to install it. You're looking for:

The 2007 Office System Driver: Data Connectivity Components.

A:

A 64-bit version of the 'Microsoft Access Database Engine 2010 Redistributable' that will allow you to use the 'Microsoft.ACE.OLEDB.12.0' provider is available here:
http://www.microsoft.com/en-us/download/details.aspx?id=13255
If you use the download from the accepted answer, you will need to build for x86, as pointed out by @backtestbroker.com.

A:

depending on the app(32/64bit) using the connection you could just install

Access 2007 engines (only 32bit)
Access 2010 (32&64bit)
Access 2013 full runtime (32&64bit ! >200mb)
Access 2016 runtime
Access 2019 runtime

Summary:

all offices from 2007-2016 contain the provider "Microsoft.ACE.Oledb.12.0"
depending on your application architecture choose the appropriate runtime engine (32/64)6
check your providers with the powershell-command from both 32 and 64bit shell:
(New-Object system.data.oledb.oledbenumerator).GetElements() | select SOURCES_NAME, SOURCES_DESCRIPTION 

and you will see which provider your system can use

the long story:
the strings can be found with http://live.sysinternals.com/strings.exe
eg. on a 64bit System with 32bit drivers installed
strings.exe -u -n 10 "c:\Program Files (x86)\Common Files\microsoft shared\OFFICE12\MSO.DLL" | findstr "ACE.O"
strings.exe -u -n 10 "c:\Program Files (x86)\Common Files\microsoft shared\OFFICE14\MSO.DLL" | findstr "ACE.O"
strings.exe -u -n 10 "c:\Program Files (x86)\Common Files\microsoft shared\OFFICE15\MSO.DLL" | findstr "ACE.O"

even in the upcoming office 2016
c:\Program Files\Microsoft Office\root\VFS\ProgramFilesCommonX64\Microsoft Shared\OFFICE16\MSO.DLL
c:\Program Files\Microsoft Office\root\VFS\ProgramFilesCommonX86\Microsoft Shared\OFFICE16\MSO.DLL

you will find the strings 

Microsoft.ACE.OLEDB
Microsoft.ACE.Oledb.12.0

the Office 2013 comes also with csi.dll
c:\Program Files (x86)\Common Files\microsoft shared\OFFICE15\Csi.dll
c:\Program Files\Common Files\Microsoft Shared\OFFICE15\Csi.dll

which contains the "Microsoft.ACE.OLEDB.15.0"
and Office 2016
c:\Program Files\Microsoft Office\root\VFS\ProgramFilesCommonX64\Microsoft Shared\OFFICE16\Csi.dll
c:\Program Files\Microsoft Office\root\VFS\ProgramFilesCommonX86\Microsoft Shared\OFFICE16\Csi.dll

which has the "Microsoft.ACE.OLEDB.16.0" version

