MSIX Installer for Office: Microsoft giving up on the idea?

Timeline For Office 365 Evolution

2017 - Office is published in the Microsoft Store. This is not in MSIX format. It is still Win32 applications wrapped under the appx format

2018 - The MSIX installer type is announced, along with the statement that all Microsoft product installers from the store will be migrated to this format.

2019 - IT Professionals start converting different apps and try Office as well. Limitations affect the Office app.

2021 - John Vintzel, the head of the MSIX development department, publicly states that they are working hard to create an MSIX version of Office

2021-2025 - Silent treatment: no announcements about Office 365 in MSIX format. Some improvements are made to the MSIX in general

2025 - Official Statement of Office retiring from Microsoft Store. No more feature updates

2026 - Last year for security updates

Why? Technical Involvements

MSIX is great in theory, especially in terms of security, strong update mechanisms, and direct integration with Windows OS.

However, it has some limitations.

What is Office 365 from an application build perspective? It does not represent a single app. It’s like an entire ecosystem where you can add COMS and Add-ins.

You have Word, Excel, Outlook, Access, and so on, each with its own Add-in. These components must all be able to communicate with one another while remaining in a symbiotic state with the operating system.

Here are some MSIX limitations and how they affect Office:

• Virtual Registry Isolation: MSIX runs in a sandbox with a "Virtual Registry". However, Office uses COM registration to establish connections to third-party add-ins (such as PDF creators, CRM plugins, or Excel macros). The MSIX "bubble" served as a firewall, preventing these plugins from "seeing" or connecting to Office.
• Update Channel Rigidity: Click-to-Run allows enterprise admins to manage specific update "channels" (Monthly, Semi-Annual, etc.). MSIX’s modern update mechanism is much less customizable, making it a nightmare for IT departments that need tight control over when new versions are delivered to users.
  
• Process Inter-Communication: Office apps form a "symbiotic family." Word needs to call Excel to embed a chart, Outlook needs to call Word for email editing, and so on. MSIX’s strict security isolation makes cross-communication extremely difficult to handle without breaking the security sandbox, which voids MSIX’s entire security foundation.
• Shell Extension: After you install Office, you will notice that when you right-click in different documents or email messages, different Office integrations appear in the Windows Shell. MSIX containers generally do not support these types of in-process shell extensions, which would result in the loss of core Windows integration features.

What does this mean for MSIX in general?

Now that we know that Microsoft has given up on Office as MSIX, at least for the time being, what does it mean for MSIX technology? Is there any impact?

MSIX adoption has been up and down, despite the availability of Office 365 in MSIX format.

In the first years, direct conversion was difficult. Using only Microsoft’s MSIX packaging tool, the success rate was around 20%. Keep in mind that the success rate is highly subjective and depends on the application to be migrated.

However, the apps chosen for migration in the earlier tests were the so-called core applications used in enterprise environments, such as Notepad++, VLC, Adobe Reader, 7-Zip, WinSCP, and so on.

With the help of Advanced Installer with the PSF (Package Support Framework) fixup, the success rate could be increased by 50-60%. However, this would still be considered low for enterprise environments.

Over time, Microsoft added more support for MSIX, but limitations still remain, and some applications cannot be converted.

MSIX will not disappear, nor will it replace MSI or EXE installers. It is not just up to IT professionals to convert these applications into MSIX. It starts with the application vendors that build the software and the installers. And so far, we are not seeing them offer installers in MSIX installers alongside the classic ones. It’s no one's fault.

Some applications required more resources to make sure that all the features could work properly. That's why limiting them to the MSIX requirements will not be effective.

Final Takeaways

• In 2018, Microsoft announced MSIX as the next big thing: a single installer that would replace MSI, EXE, and APP-V.
• By 2026, there will be no Office applications in MSIX format. There is an MS Store for Microsoft 365 (Office apps), but it is not in MSIX format. Microsoft is pulling the plug here.
• Feature updates officially ended in October 2025, and security updates will end in December 2026.
• Here are some of the MSIX limitations and how they affect Office: Virtual Registry Isolation, Update Channel Rigidity, Process Intercommunication, and Shell Extension.
• Direct conversion proved difficult in the early years. Using only Microsoft's MSIX packaging tool, the success rate was about 20%.
• This success rate could be increased by 50-60% by combining Advanced Installer with the PSF (package support framework) fixup. However, this would still be considered low in enterprise settings.
• Microsoft has gradually increased support for MSIX, but there are still limitations, and some applications cannot be converted.
• MSIX will not go away, nor will it replace MSI or EXE installers.
• Some applications required additional resources to ensure that all of their features functioned properly. That is why limiting them to MSIX requirements will not suffice.

Conclusion

So, has Microsoft given up on MSIX? No, not really. However, when it comes to Office, they have clearly stepped back.

Office was supposed to be the flagship example, demonstrating that MSIX could handle even the most complex Microsoft workload. That never happened.

In the end, Click-to-Run remained the only realistic option. Not because MSIX is bad technology, but because Office is simply too complex, too integrated, and too reliant on deep Windows hooks to fit comfortably inside a strict container.

What this shows is something more grounded: MSIX has its place, but it is not the universal replacement many expected back in 2018. MSI and EXE are not going anywhere. Click-to-Run is staying. And MSIX will continue to exist in places where it makes sense.