New Outlook Will Not Open Attachments in Desktop Apps

Question

New Outlook Will Not Open Attachments in Desktop Apps

Jacob Wiggs 40

The expected flow it as follows:

User receives email with file attached > User previews file, or right clicks on the file > User selects the option to open the file in the Desktop version of an app (Adobe, Excel, Word, etc. same issue across all) > App opens the file

Instead of this, though, we are receiving the following flow:

User receives email with file attached > User previews file, or right clicks on the file > User selects the option to open the file in the Desktop version of an app (Adobe, Excel, Word, etc. same issue across all) > Outlook does 1 of 2 things, depending on the exact method used to try to open the file:

1. It brings up an error stating something along the lines of "Can't open file, please restart Outlook and try again"
1. It says "Opening file..." on a loading bar at the bottom, then the bar disappears.

After both of these, the file never opens.

I have this issue happening with 2 different users. The one user I am currently able to get the information from has an Outlook Version section as follows:

Microsoft Outlook Version: 1.2026.1013.100

Client Version: 20261016004.16

WebView2 Version: 156.0.4314.50 (Stable)

And has an Office build of:

16.0.20527.20088

For this User, I have also included logs from the Procmon application which I ran filtering for excel.exe and olk.exe. I verified with our SOC team that there are no blocks happening from our EDR application. I also verified that the files can be opened if downloaded, if using the the "Open in Excel (Web App)" option, and if using old Outlook. It appears to be linked specifically to the integration between New Outlook and desktop apps (both Microsoft, and Third Party, as PDFs won't open in Acrobat as briefly noted above.

Jacob Wiggs 40 Reputation points

2026-10-30T13:46:45.96+00:00

For anyone who may be experiencing this issue, as noted below it was an issue with WebView2. An update has been pushed out and our users that had this issue have reported that it is working normally now.
Jayvee Michael Zuniga 0 Reputation points

2026-11-02T18:35:27.8833333+00:00

Hello.. we are experiencing the same issue in our company and several users are affected. What's the update that fixes it? Is there any work arounds? Thank you in advance for the responses.

Answer accepted by question author

Hin Vo 1,745 Independent Advisor

Hi @Jacob Wiggs

Recently, I have found multiple user reports regarding this issue. For now, this issue appears to be related to Microsoft Edge WebView2 Runtime 156.x. From what I understand, attachments fail to open from New Outlook when using WebView2 versions 156.0.4314.42 and 156.0.4314.50, while the same attachments open successfully after configuring New Outlook to use WebView2 Fixed Version Runtime 155.0.4283.62 instead. This behavior appears to indicate a regression in the WebView2 156.x runtime branch.

Reference: https://github.com/MicrosoftEdge/WebView2Feedback/issues/5782

Since your environment is also running WebView2 Runtime 156.x, it is possible that your New Outlook installation is being affected by the same issue.

As a temporary workaround, you may consider using Classic Outlook while this issue is being investigated. Additionally, I would recommend submitting feedback directly from New Outlook via: Help > Feedback > Report a problem. This will ensure the issue is routed to the Outlook product team for visibility and investigation. Based on the reports observed so far, the team may already be aware of the issue and could provide a fix in a future update.

User's image

I hope this helps.

Jacob Wiggs 40 Reputation points

2026-10-28T14:30:20.31+00:00

Thank you! Did some more digging after posting this and found the issue on GitHub for this as well, but thanks for the response! The more visibility, the better!
Hin Vo 1,745 Reputation points Independent Advisor

2026-10-28T14:37:16.6+00:00

Hi @Jacob Wiggs

Thank you for your feedback. I hope this issue will be resolved soon.
Alberto Vega 0 Reputation points

2026-10-28T16:49:20.3833333+00:00

Got the same issue, hoping it will be done soon.
Marcus Baker 0 Reputation points

2026-10-29T20:53:41.85+00:00

We are having the exact same issue. Please resolve this Microsoft and issue an update

2 additional answers

Your answer

Jacob Wiggs 40 Reputation points

2026-10-30T13:46:45.96+00:00

For anyone who may be experiencing this issue, as noted below it was an issue with WebView2. An update has been pushed out and our users that had this issue have reported that it is working normally now.
Jayvee Michael Zuniga 0 Reputation points

2026-11-02T18:35:27.8833333+00:00

Hello.. we are experiencing the same issue in our company and several users are affected. What's the update that fixes it? Is there any work arounds? Thank you in advance for the responses.
Jacob Wiggs 40 Reputation points

2026-10-28T14:30:20.31+00:00

Thank you! Did some more digging after posting this and found the issue on GitHub for this as well, but thanks for the response! The more visibility, the better!
Hin Vo 1,745 Reputation points Independent Advisor

2026-10-28T14:37:16.6+00:00

Hi @Jacob Wiggs

Thank you for your feedback. I hope this issue will be resolved soon.
Alberto Vega 0 Reputation points

2026-10-28T16:49:20.3833333+00:00

Got the same issue, hoping it will be done soon.
Marcus Baker 0 Reputation points

2026-10-29T20:53:41.85+00:00

We are having the exact same issue. Please resolve this Microsoft and issue an update

Answer 1

The exact New Outlook, client, and WebView2 versions reported match a current attachment-launch regression, so keep users on Classic Outlook or Download/Open while escalating the build-specific failure rather than changing EDR, file associations, or Office Trust Center settings.^1^

New Outlook officially supports opening Office attachments in desktop applications, so this is not expected product behavior.^2^

Check the OLK attachment staging folder

Before escalating, test the one local condition specifically associated with New Outlook failing to transfer attachments to desktop applications:

Close New Outlook.
Press Windows+R.
Enter:
```
   %LOCALAPPDATA%\Microsoft\Olk
```
Check for a folder named Attachments.
If it is missing, create a folder named exactly Attachments.
Start New Outlook and retest Open in desktop app.

A matching New Outlook case found that the operation failed when this staging folder was absent and worked after it was created.^3^

If the folder already exists, do not delete it or its contents solely as a speculative repair. That would not address the reported exact-version regression.

Build-specific finding

The reported combination is:

New Outlook 1.2026.1013.100
Client 20261016004.16
WebView2 156.0.4314.50

A WebView2 issue reports attachment-launch failures with that exact New Outlook/client combination and WebView2 156.0.4314.42 or .50; it identifies 155.0.4283.62 as the last observed working runtime.^4^ (GitHub-hosted issue—review its maintainer updates before acting.)

Do not manually downgrade WebView2 across production devices based only on that report. No supported rollback procedure or confirmed fixed runtime is supplied here, and WebView2 is shared by other applications. Deploy the corrected New Outlook/WebView2 update through your normal update-management process once Microsoft publishes it.

Microsoft’s published New Outlook known-issues page does not currently document this particular failure or an official fix.^5^

Escalate with the existing evidence

Since downloading, the web app, and Classic Outlook work—and EDR blocking has already been ruled out—open a Microsoft 365 support request:

Microsoft 365 admin center → Help & support.
Enter the attachment-launch symptom.
If suggested results do not resolve it, select Contact Support.
Include:
- All three version numbers.
- Both affected users and when the behavior began.
- Reproduction steps for Excel and PDF/Acrobat.
- Confirmation that Download/Open, Office for the web, and Classic Outlook work.
- Whether %LOCALAPPDATA%\Microsoft\Olk\Attachments existed.
- Procmon traces filtered to olk.exe, excel.exe, and the relevant PDF application.
- The matching WebView2 issue reference.

An administrator with an eligible Microsoft 365 subscription can create the request online; partner-purchased subscriptions should be escalated through the partner.^6^

Avoid the Classic Outlook cache, COM add-in, mouse double-click, Protected View, and linked-attachment registry fixes: those sources concern different clients or symptoms, while this failure affects New Outlook’s desktop-app handoff across ordinary Office and PDF attachments.

References

Answer 2

Hin Vo 1,745 Independent Advisor

Hi @Jayvee Michael Zuniga

As an update regarding the known issue EX1528992 - Users may not be able to open email file attachments or see the "Open" option in the new Outlook desktop app:

October 30, 2026, 3:32 AM GMT+7 - Microsoft has completed the deployment of a targeted fix by disabling the impacting configuration and confirmed that the issue has been remediated for affected users.

User's image

If you are still experiencing the issue, please close and reopen the new Outlook desktop app, as this change requires a client restart to take effect.

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