Excel Add-In Error

Question

Excel Add-In Error

S 0

There seems to be an Excel Add-in error in the app for Windows. Despite restarting, refreshing, signing out, updating to latest version, deleting WEF files incase of cache issues, switching between accounts -- none of them seem to work. Interestingly, the add-ins on the Excel Web work, but not in the app.

There's a recent issue on Microsoft 365 add-ins, and I'm not sure if it has been resolved?

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3 answers

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Answer 1

Yes—there are recent known Office add-in issues that can make add-ins appear missing or fail to load.

For the current known issue tied to Exchange authentication changes, the status is open with a mitigation rolling out. In that case, no customer action is required. If the problem continues, the documented next step is to contact Microsoft Support.

There is also a separate known issue where centrally deployed Office add-ins that are deployed as Optional or Available may be missing across Office clients, including Excel desktop and Excel on the web. The documented workaround for that issue is for IT admins to change the deployment type to Fixed (Default). That applies to organization-managed add-ins, not typical personal/home add-ins.

Based on the described behavior:

Excel on the web works, but the Windows desktop app does not: that is consistent with a desktop-client-specific add-in problem.
Since restart, sign-out, update, account switching, and clearing WEF cache were already tried, the remaining documented checks are:
1. Check system date and time on Windows. Incorrect date/time can prevent manifest verification.
2. Reinstall the add-in. If the package was tampered with before installation, reinstalling a fresh copy is the documented fix.
3. If Excel itself is unstable or crashing, start Excel in Safe Mode with excel /safe and test whether the add-in loads there. If it does, a conflicting add-in may be involved.
4. If recently installed add-ins are crashing Excel, Data Execution Prevention (DEP) may be disabling an add-in because of compatibility with organization IT policies.
5. If the add-in still does not load, report the issue from Office using Help > Feedback > Report a problem or contact Microsoft Support.

If this is a consumer/home scenario rather than an organization-managed deployment, the admin deployment workaround does not apply. The most relevant documented path is:

verify Windows date/time,
reinstall the add-in,
test in excel /safe,
then report it through Office feedback or Microsoft Support if it persists.

References:

Answer 2

Kai-H 27,395 Microsoft External Staff Moderator

Hi, S

Since the add-ins work in Excel for the web, the account and add-in service are probably fine. The issue is more likely with the Windows desktop environment, particularly connected experiences, WebView2, network filtering, or the Windows profile.

Here are some suggestions you can try:

In Excel, open File > Account > Account Privacy > Manage Settings, then make sure Optional connected experiences and experiences that download online content are enabled. Add-ins may not open when Office cannot connect to online services.

Open Settings > Apps > Installed apps, find Microsoft Edge WebView2 Runtime, select Modify, and run Repair. Desktop Office add-ins depend on WebView2 even when they work normally in a browser.

Temporarily test Excel using a mobile hotspot. If the add-ins load, it is recommended that your IT administrator check the firewall, proxy, SSL inspection, or antivirus rules affecting Microsoft Marketplace and WebView2.

Create a temporary Windows user account and test Excel there. If it works, the original Windows profile is damaged and should be rebuilt.

These checks isolate desktop components without repeating the troubleshooting already completed.

Thank you for your patience in reading, I hope this information has been helpful to you.

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S 0 Reputation points

2026-09-17T13:08:17.88+00:00

Hi Kai, hope all is well.

Firstly, thanks for your answer. Despite doing all your suggestions, it still does not appear to work.

I have, remodified the Microsoft Edge Web2View Runtime, which seems to be apart of Microsoft Edge when I search for it. All the 'Optional connected experiences' options are activated, yet still no fix. I've also attempted to test Excel using mobile hotspot and it did not work. Then, I created a temporary Window's account and unfortunately, the same outcome.

I am still unsure of what's causing the error/issue for add-ins because I simply cannot access any.

Thank you for your help, and for reading this.
Kai-H 27,395 Reputation points Microsoft External Staff Moderator

2026-09-21T06:32:54.09+00:00

Hi, S

Thanks for the update. Your tests are useful because the same result on a temporary Windows account and a mobile hotspot makes a profile or ordinary network problem much less likely.

I would now perform an Online Repair of Microsoft 365, not another WebView2 repair:

Close all Office applications.

Open Settings > Apps > Installed apps.

Find Microsoft 365, select the three-dot menu, then Modify.

Select Online Repair > Repair, and restart Windows when it finishes.

Afterward, update Excel through File > Account > Update Options > Update Now and record the exact build number.

If all add-ins still fail, check whether antivirus or endpoint-security software is blocking msedgewebview2.exe. Microsoft specifically identifies security software as a possible cause when Office cannot create the WebView2 process. Do not add exclusions or disable protection on a managed computer without approval from the administrator.

For a work or school account, the Microsoft 365 administrator should also check Office Store and add-in policies, including AppsForOfficeEnabled. Microsoft is currently investigating a separate issue affecting some organization-deployed add-ins configured as Optional or Available, so Service health should also be reviewed.

If Online Repair does not help, please post the exact error text and your Excel build number. At that point, repeating cache, profile, network, or WebView2 repair steps is unlikely to add much value.

Answer 3

EmilyS_726 30,010 Volunteer Moderator

Hello,

I'm having the same issue on my personal account with a Microsoft 365 Personal subscription. When I switched to my business account, it works fine on the same app.

I've noticed a growing number of users reporting the same problem on this forum. I suspect the cause is on Microsoft's side, although there's been no official statement about it yet. Unfortunately, I don't think there's anything you can do on your end to fix it.

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