New Outlook stopped opening .msg files

Question

New Outlook stopped opening .msg files

L 0

We have a few people in our org (Exchange) who very recently started getting an error when trying to open .msg files in New Outlook, and I'm curious if anyone else is seeing the same error (and if the same work around fix we've been using also works for anyone else).

When trying to open a .msg file, we very recently started seeing New Outlook open with this error:
"The New Outlook for Windows doesn't currently support this action. You can switch back to Classic Outlook for Windows and try again."
In Windows Settings, New Outlook for Windows is set to as the default for .msg files, and everything worked just fine to open .msg files until the last day or two.
-- If the .msg email file is opened by double clicking it, New Outlook opens with the "The New Outlook for Windows doesn't currently support this action. You can switch back to Classic Outlook for Windows and try again." error message.
-- If the .msg email file is opened using right-click > open with > Outlook (new) is selected, the email opens in New Outlook just fine as expected, but any other .msg email files that are double clicked will still give the error message and not open.

-- Work around fix: If the .msg email file is opened using right-click > open with > Choose another app > Outlook (new) > Always, the email opens in New Outlook just fine as expected, AND double clicking any future .msg files open in New Outlook without issue.

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5 answers

Your answer

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Answer 1

I believe we may have identified the issue.

According to this article (Start new users in new Outlook | Microsoft Learn) each file type uses a different program ID (ProgId)

<Association Identifier=".eml" ProgId="AppXn1scph4yxkh5tvym038c6zjjfpmdg2fg" ApplicationName="Outlook" />
<Association Identifier=".ics" ProgId="AppX18q1gk8kdws5gt2g5c62cxc6qydq7tsw" ApplicationName="Outlook" />
<Association Identifier=".msg" ProgId="AppXtked0qbwdp1v44z1p7ts8bc7kkwea1mh" ApplicationName="Outlook" />
<Association Identifier=".oft" ProgId="AppXbyq8sebsp9xh069xkxaaystpjztdp9h3" ApplicationName="Outlook" />
<Association Identifier="mailto" ProgId="AppXbx2ce4vcxjdhff3d1ms66qqzk12zn827" ApplicationName="Outlook" />
<Association Identifier="webcal" ProgId="AppX4vt5c8cbxd42btbp6br6zs9v25a1kh5j" ApplicationName="Outlook" />

When we checked our policies, it looks like AppXbx2ce4vcxjdhff3d1ms66qqzk12zn827 (the one that should be used for mailto) was being pushed to .eml, .ics, & .msg also. We are working internally to update the default ProgId being pushed to our computers to match what Microsoft recommends in their article.
FYI incase anyone else runs into a similar issue.

Answer 2

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Answer 3

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Answer 4

Jade Ng 16,620 Microsoft External Staff Moderator

Dear L,

From what you describe, the issue appears to be related to the file association for .msg files

I tested this in my own environment using new Outlook for Windows. Opening a .msg file with right-click > Open with > New Outlook worked as expected. Double-clicking the .msg file also opened it in new Outlook without any error. I was therefore unable to reproduce the behavior you describe.

To help me narrow down the issue, could you please confirm the following?

Does the error occur with only one specific .msg file, or with all .msg files you try to open?
How was the affected .msg file created? For example, was it saved or downloaded from classic Outlook, new Outlook, Outlook on the web, or received from another person?
Approximately how many users in your organization are affected, and do they share anything in common, such as the same device model, Windows version, or new Outlook version?

In the meantime, you can drag and drop the .msg file onto the reading pane in new Outlook. Please also note that opening .msg and .oft files in new Outlook require an account with a qualifying Microsoft 365 subscription.

User's image

For reference, please refer to this article Open .eml, .msg, and .oft files in new Outlook and Outlook on the web

Please reply below if you have any update. Thank you very much for your time and your cooperation.

Looking forward to hearing from you.

L 0 Reputation points

2026-11-04T09:47:15.2666667+00:00

We have seen this behavior when the impacted users tried to open any. Msg email. We tested with multiple .msg email files saved from classic Outlook - both older files saved from classic Outlook (from over a year ago), and files we tested saving from classic Outlook today.

We know of at least 5 impacted users (myself included).

We haven’t found any specific commonality between the users but we’re still collecting details. Considering how quickly it started, we currently suspect a Windows update or New Outlook update.
Jade Ng 16,620 Reputation points Microsoft External Staff Moderator

2026-11-05T08:09:55.77+00:00
Dear L,

Thank you for the update. Since only some users in your organization are affected, the next step is to check whether the issue follows the user account or the device. Could you please run the following test?

Choose one user who is not affected, and one user who is affected.

On the unaffected user's computer, sign in to Windows with the affected user's account. If a separate Windows sign-in is not possible, sign in to new Outlook with the affected account instead.

Try to open a few .msg files by double-clicking them, and note whether the same error appears.

If possible, repeat the test the other way around. Sign in with the unaffected user's account on the affected computer and try the same .msg files.

Thank you for your patience and cooperation. I am looking forward to your response!
Jade Ng 16,620 Reputation points Microsoft External Staff Moderator

2026-11-09T04:48:50.67+00:00

Dear L,

May I know if you have any updates from your end? I am looking forward to your response.
L 0 Reputation points

2026-11-09T18:09:54.2966667+00:00

Thank you for the follow up. I believe we have identified the issue - we had a policy that was pushing out program id AppXbx2ce4vcxjdhff3d1ms66qqzk12zn827 for eml, msg, and ics file types, but according to a Microsoft article, there are different program ids for each file type, and the AppXbx2ce4vcxjdhff3d1ms66qqzk12zn827 is only for mailto. I made an additional post with more information about this, but I believe this was the cause.

Answer 5

Your Open with → Choose another app → Outlook (new) → Always workaround is the correct immediate fix because it rewrites the .msg association used by File Explorer, even when Windows Settings already displays New Outlook as the default.

Microsoft documents that New Outlook supports opening .msg files by double-click, right-click, or drag-and-drop. If double-click fails, its guidance is to reset the default application for that file type.^1^

Per-user resolution

For each affected user:

Exit New Outlook.
Right-click any .msg file in File Explorer.
Select Open with → Choose another app.
Select Outlook (new).
Select Always.
Double-click a different .msg file and verify that it opens.

Selecting Open with → Outlook (new) without choosing Always only opens that individual file; it does not rebuild the persistent association. That matches your observation exactly.

Organization-wide configuration

If this begins affecting more users or newly provisioned devices, deploy a Windows default-app association for .msg. Microsoft documents this New Outlook association:^2^

<DefaultAssociations>
  <Association
    Identifier=".msg"
    ProgId="AppXtked0qbwdp1v44z1p7ts8bc7kkwea1mh"
    ApplicationName="Outlook" />
</DefaultAssociations>

Import or deploy that XML through your normal Windows default-application association policy. Test it against your managed Windows build first, particularly if Classic Outlook is also installed.

What the error does—and does not—mean

The message claiming that New Outlook “doesn't currently support this action” is misleading in this scenario. .msg opening is a documented New Outlook feature, although .msg and .oft files require an account with a qualifying Microsoft 365 subscription.^1^

No entry on Microsoft’s current New Outlook known-issues page identifies this exact recent .msg double-click regression.^3^ Therefore, the available evidence supports treating this as a file-association failure rather than a confirmed service incident or removal of .msg support.

If resetting the association stops working

Use these fallbacks in order:

Open New Outlook and drag the .msg file onto its reading pane; Microsoft documents this as a supported opening method.^1^
Temporarily associate .msg with Outlook (classic/desktop) if installed.
Capture the New Outlook version, Windows build, timestamp, and whether both Outlook clients are installed, then open a Microsoft 365 support case. Include that explicit Open with → Outlook (new) succeeds while double-click fails until Always is selected; that distinction isolates the Explorer association path.

References