MSI File Extension

What is MSI file?

Files with .MSI filename extension store application installation package or a driver package for Microsoft Windows. MSI files have standardized structure defined by metadata and contain resources needed to install an application. The name MSI is derived from the name Microsoft Installer, as the original installation packages were referred to before the name has been changed to Windows Installer.

MSI package structure

MSI packages are nothing more than relational databases save in OLE/COM Structured Storage File format. MSI files are divided into the following parts:

• One or more products to be installed,
• Product components,
• Functions – features, a larger hierarchical structures comprised of components; optional installation features,
• Key paths for components, critical elements for each component needed during component installation or uninstallation.

Although installers may provide multiple products, they cannot be used to verify dependencies between the products. Dependencies are generated by uninstaller tools or via GUI. MSI was the recommended method for installing products on Windows platforms before Microsoft introduced its Microsoft Store service, as it allowed clean versioning and dependency resolution between packages.

Creating and using Windows installer packages

MSI installer packages are created using dedicated tool developed by Microsoft. MSI is just one on many installer formats supported on Windows. MSI installation process is divided into the following phases:

1. User interface, where users set installation options,
2. Execution – actual installation process; two modes are available:
   • Instant, mode
   • Pending mode.
3. Rollback – if the installation fails for some reason, the transaction is rolled back and no changes are made in the system.

Contents of MSI packages can be extracted by using certain decompression tools.

Versions of Windows installer

MSI packages were introduced along with the debut of Office 2000 in 1999 (MSI versions 1.0). Version 5.0 was published in 2009 when Windows 7 and Windows Server 2008 R2 were released. Similar to the MSI is the less popular MSP format. MSI format was replaced by newer MSIX standard in 2018. MSIX combines MSI, APPX, APP-V, and ClickOne technologies in a single installer package for better security, reliability, and cross-platform support.

Programs which support MSI file extension

Programs that can handle MSI files are as follows. MSI files can be encountered on all system platforms, including mobile, yet there is no guarantee each will properly support such files.

Updated: 02/21/2022

How to open file with MSI extension?

Being unable to open files with MSI extension can be have various origins. On the bright side, the most encountered issues pertaining to Windows Installer Package files aren’t complex. In most cases they can be addressed swiftly and effectively without assistance from a specialist. The following is a list of guidelines that will help you identify and solve file-related problems.

Step 1. Download and install Windows Installer

Problems with opening and working with MSI files are most probably having to do with no proper software compatible with MSI files being present on your machine. The most obvious solution is to download and install Windows Installer or one to the listed programs: Microsoft Windows, 7-Zip, Windows Installer XML. The full list of programs grouped by operating systems can be found above. The safest method of downloading Windows Installer installed is by going to developer’s website (Microsoft Corporation) and downloading the software using provided links.

Step 2. Update Windows Installer to the latest version

If the problems with opening MSI files still occur even after installing Windows Installer, it is possible that you have an outdated version of the software. Check the developer’s website whether a newer version of Windows Installer is available. Software developers may implement support for more modern file formats in updated versions of their products. This can be one of the causes why MSI files are not compatible with Windows Installer. The latest version of Windows Installer should support all file formats that where compatible with older versions of the software.

Step 3. Associate Windows Installer Package files with Windows Installer

If you have the latest version of Windows Installer installed and the problem persists, select it as the default program to be used to manage MSI on your device. The process of associating file formats with default application may differ in details depending on platform, but the basic procedure is very similar.

Selecting the first-choice application in Windows

• Choose the Open with entry from the file menu accessed by right-mouse clicking on the MSI file
• Click Choose another app and then select More apps option
• Finally select Look for another app on this PC, point to the folder where Windows Installer is installed, check the Always use this app to open MSI files box and conform your selection by clicking OK button

Selecting the first-choice application in Mac OS

• From the drop-down menu, accessed by clicking the file with MSI extension, select Information
• Find the Open with option – click the title if its hidden
• Select Windows Installer and click Change for all...
• If you followed the previous steps a message should appear: This change will be applied to all files with MSI extension. Next, click the Continue button to finalize the process.

Step 4. Check the MSI for errors

Should the problem still occur after following steps 1-3, check if the MSI file is valid. Being unable to access the file can be related to various issues.

1. The MSI may be infected with malware – make sure to scan it with an antivirus tool.

Should it happed that the MSI is infected with a virus, this may be that cause that prevents you from accessing it. It is advised to scan the system for viruses and malware as soon as possible or use an online antivirus scanner. If the scanner detected that the MSI file is unsafe, proceed as instructed by the antivirus program to neutralize the threat.

2. Ensure the file with MSI extension is complete and error-free

If the MSI file was sent to you by someone else, ask this person to resend the file to you. During the copy process of the file errors may occurred rendering the file incomplete or corrupted. This could be the source of encountered problems with the file. If the MSI file has been downloaded from the internet only partially, try to redownload it.

3. Check if the user that you are logged as has administrative privileges.

There is a possibility that the file in question can only be accessed by users with sufficient system privileges. Switch to an account that has required privileges and try opening the Windows Installer Package file again.

4. Make sure that the system has sufficient resources to run Windows Installer

If the systems has insufficient resources to open MSI files, try closing all currently running applications and try again.

5. Ensure that you have the latest drivers and system updates and patches installed

Latest versions of programs and drivers may help you solve problems with Windows Installer Package files and ensure security of your device and operating system. It is possible that one of the available system or driver updates may solve the problems with MSI files affecting older versions of given software.

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