New Outlook – Unable to Open Documents from Group Mailbox

Question

New Outlook – Unable to Open Documents from Group Mailbox

Anushka Thakur 0

Screenshot 2026-09-08 173920

Hello,

One of our users is experiencing an issue with New Outlook. The user is unable to open documents/attachments from a group mailbox.

Documents from the user’s personal inbox open without any issue.
Documents from the group mailbox do not open in New Outlook.
We tested the same group mailbox in Outlook on the Web (OWA) and Classic Outlook, and the user can open the documents successfully in both.
We also tried creating a new Outlook profile. This resolved the issue temporarily, but after some time, the same issue occurred again.

The issue appears to happen only in New Outlook when accessing documents from the group mailbox.

Could you please advise what may be causing this issue and how we can resolve it?

Thank you.
Anushka

Jack-Bu 6,960 Reputation points Microsoft External Staff Moderator

2026-10-14T18:23:47.5666667+00:00
Hello Anushka,

I understand that attachments from the group mailbox fail to open in New Outlook, although they work correctly in Outlook on the Web and Classic Outlook.

Since recreating the Outlook profile only resolved the issue temporarily, could you please try the following?

Save the attachment locally: In New Outlook, select Save as instead of opening the preview, and check whether the downloaded document opens successfully.

Check the mailbox configuration: If this is a shared mailbox, go to Settings > Accounts > Shared with me and check how the mailbox is added. If the option is available and the user has Full Access permission, try adding it as an account.

Clear New Outlook's local cache You can also try repairing or resetting New Outlook to clear possible issues with its locally stored data.

Close New Outlook.

Press Windows + I to open Settings.

Go to Apps > Installed apps.

Find Outlook (new) and click the three dots (...) next to it.

Select Advanced options > Repair.

Reopen Outlook and check whether the attachments open correctly.

Restart New Outlook: Close the application completely, reopen it, and test the attachment again. You can refer to this guide: Manage shared mailbox settings in New Outlook.)

If the issue persists, could you please confirm:

Is this a shared mailbox or a Microsoft 365 Group mailbox?

Does the issue affect all attachment types or only certain files, such as PDF or Word documents?

Does Save as work even when the preview fails?

These details will help narrow down the cause.

Note: Please follow the steps in [our documentation] to enable e-mail notifications if you want to receive the related email notification for this thread.

2 answers

Your answer

Jack-Bu 6,960 Reputation points Microsoft External Staff Moderator

2026-10-14T18:23:47.5666667+00:00

Hello Anushka,

I understand that attachments from the group mailbox fail to open in New Outlook, although they work correctly in Outlook on the Web and Classic Outlook.

Since recreating the Outlook profile only resolved the issue temporarily, could you please try the following?

Save the attachment locally: In New Outlook, select Save as instead of opening the preview, and check whether the downloaded document opens successfully.

Check the mailbox configuration: If this is a shared mailbox, go to Settings > Accounts > Shared with me and check how the mailbox is added. If the option is available and the user has Full Access permission, try adding it as an account.

Clear New Outlook's local cache You can also try repairing or resetting New Outlook to clear possible issues with its locally stored data.

Close New Outlook.

Press Windows + I to open Settings.

Go to Apps > Installed apps.

Find Outlook (new) and click the three dots (...) next to it.

Select Advanced options > Repair.

Reopen Outlook and check whether the attachments open correctly.

Restart New Outlook: Close the application completely, reopen it, and test the attachment again. You can refer to this guide: Manage shared mailbox settings in New Outlook.)

If the issue persists, could you please confirm:

Is this a shared mailbox or a Microsoft 365 Group mailbox?

Does the issue affect all attachment types or only certain files, such as PDF or Word documents?

Does Save as work even when the preview fails?

These details will help narrow down the cause.

Note: Please follow the steps in [our documentation] to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 1

Hi Anushka,

Since the attachments open perfectly fine in Classic Outlook and OWA, and recreating the profile only provided a temporary fix, this confirms that the issue is strictly related to the New Outlook client's local cache or its built-in document previewer.

Here is the best approach to resolve this for your user:

1. The Immediate Workaround (Avoid the Previewer) As seen in your screenshot, the error explicitly states "Something went wrong while the document preview was being created". The actual file is not corrupted.

Tell the user to simply click the "Save as" button right below that error message to download the file locally. They can then open it directly from their computer until the app is permanently fixed.

2. Repair and Reset the New Outlook App Since recreating the profile failed to hold, you need to clear the app's deeply stored local data.

Go to Windows Settings > Apps > Installed apps.

Search for Outlook (new), click the three dots (...), and select Advanced options.

Scroll down and click Terminate, then click Repair.

Test the mailbox. If it still fails, go back to the same menu and click Reset. (Note: This clears local data and will require the user to sign back in).

3. Reinstall from the Microsoft Store

If the Reset fails, the local client might be fundamentally broken.

Uninstall Outlook (new) completely from the Installed Apps menu.

Open the Microsoft Store, search for "Outlook for Windows", and reinstall it.

If the issue still returns after a clean reinstall, this is a bug with the New Outlook preview path for group mailboxes, and you will need to raise a Microsoft 365 Support case so their engineering team can investigate it.

Answer 2

Repair or reset the New Outlook for Windows app, because the same attachments work in OWA and classic Outlook while recreating the profile only clears the problem temporarily.

Repair or reset New Outlook

On Windows 11:

Close New Outlook.
Open Start → Settings → Apps → Installed apps.
Find Outlook (new), select … → Advanced options.
Select Terminate, then Repair.
Reopen Outlook and test an affected attachment from the group mailbox.
If it still fails, return to the same page and select Reset.

Reset warning: Reset clears the app’s local data and may require the user to add or sign in to accounts again. It does not delete mailbox data stored in Microsoft 365. Windows documents Repair first and Reset when repair does not resolve the app problem.^1^

Since a new profile already produced only a temporary improvement, creating another profile is unlikely to be a durable solution.

If reset does not resolve it

Uninstall and reinstall New Outlook:

Open Start and locate Outlook (new).
Expand its options and select Uninstall.
Open Microsoft Store.
Search for new Outlook for Windows, select Get, and complete account setup.
Test the same group-mailbox message before changing other settings.

Microsoft documents reinstalling New Outlook as the next recovery action for client failures.^2^

Also install any available Windows and Microsoft Store updates before retesting. New Outlook is distributed as a Store application, and Store updates can contain its client fixes.

Immediate workaround

The screenshot shows that attachment retrieval is still offering Save as, while creation of the embedded preview is failing. Until the client is fixed:

Select Save as beneath the preview error, or open the attachment menu and select Save As.
Save the file to a local folder.
Open it directly in Word, Excel, Adobe Reader, or the applicable application.

New Outlook supports selecting a different save location from the attachment menu.^3^ OWA or classic Outlook can remain the alternative if saving from New Outlook also fails.

What the test results establish

The current Microsoft New Outlook known-issues list does not identify this exact scenario—attachments from a group mailbox failing to preview while the same item works in OWA and classic Outlook—as a published limitation or current named incident.^4^

The tests narrow the failure to New Outlook’s local client or preview path:

The attachment itself is accessible in OWA and classic Outlook.
The user has sufficient mailbox access to open it through those clients.
Personal-mailbox attachments work.
Recreating the profile temporarily changes the behavior.

That does not establish the exact underlying cause, so mailbox permissions, attachment corruption, classic Outlook profile repair, PST/OST repair, and classic Outlook previewer settings should not be the initial focus.

Escalation

If the issue returns after Reset and a clean reinstall, raise a Microsoft 365 support case and include:

New Outlook version from Settings → General → About Outlook.
Windows version.
Exact timestamp and time zone of a reproduced failure.
Whether Save as succeeds despite preview failing.
File types affected and whether every group-mailbox attachment is affected.
Confirmation that the identical message works in OWA and classic Outlook.
The screenshot and a screen recording if permitted.
Whether another user or another Windows device can reproduce the problem against the same group mailbox.

Ask support to investigate the New Outlook group-mailbox attachment preview path, rather than a general mailbox-permission problem. The classic Outlook automated troubleshooters and Support and Recovery Assistant procedures are not applicable to New Outlook.^5^

References