Outlook web not allowing users to preview or download pdf attachments

Question

Outlook web not allowing users to preview or download pdf attachments

Andre Robertson 0

We have tried edge and chrome. This effects multiple users. During the day it will work and then suddenly stop working. Then later in the same day it starts working again. According to online forums and other sources, they say this issue has been resolved by 4th September but still today this is effecting many users.

We have a business basic license so can only use Outlook web. Is there a fix for this that I've missed please?

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4 answers

Your answer

Answer 1

Hi Andre,

Thank you for providing the additional details.

There was a previous Exchange Online service advisory, EX1275040, concerning users who were unable to open or download attachments in Outlook on the web. However, that advisory was reported in April 2026, so I cannot confirm that the current issue is related to the same incident.

If you are a IT administrator, you can review the advisory and check for any current Exchange Online incidents through the https://admin.cloud.microsoft/?#/servicehealth/:/alerts/EX1275040. If you do not have administrator access, please contact your organization’s IT administrator and ask them to check the Service health section in the Microsoft 365 admin center.

You may also find it helpful to review the following Microsoft Community discussions, where other organizations reported similar behavior involving attachment downloads in Outlook on the web:

While the issue is occurring, you may try the following temporary workarounds:

Open Outlook on the web in an InPrivate or Incognito browser window.
Test an affected account using a different network, such as a mobile hotspot. This can help determine whether a proxy, firewall, or security inspection service is contributing to the issue.
From the attachment menu, select Save to OneDrive, if the option is available, and then open the PDF from OneDrive. You can find more information in Open, save, and edit attachments received in Outlook.
If permitted by your organization, test the attachment using the Outlook mobile app as a temporary alternative.

If the issue continues, I recommend asking your IT administrator to open a support request through the Microsoft 365 admin center so that Microsoft Support can investigate the affected tenant and users. They can follow steps from this link: Get support - Microsoft 365 admin | Microsoft Learn

I hope this information helps. Please let me know if you have any questions or need further assistance.

Best regards.

Kristen Tran 2,120 Reputation points Independent Advisor

2026-09-25T07:24:17.3666667+00:00

Hi Andre,

Have you had a chance to review the information provided? Any updates would be greatly appreciated.
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Answer 2

Andre Robertson 0

Sorry for taking so long to respond, I have responded to your message below

Open Outlook on the web in an InPrivate or Incognito browser window.
- Done this but no change.
Test an affected account using a different network, such as a mobile hotspot. This can help determine whether a proxy, firewall, or security inspection service is contributing to the issue.
- Done this and it works fine on a different network
From the attachment menu, select Save to OneDrive, if the option is available, and then open the PDF from OneDrive. You can find more information in Open, save, and edit attachments received in Outlook.
- There's no option to save to OneDrive
If permitted by your organization, test the attachment using the Outlook mobile app as a temporary alternative.
- Outlook classic works fine but none of the users have the license for that so they can't use it for very long. I haven't tried the mobile app.

We got someone to investigate the network and all was working fine so we've ruled that out. The customer is still having the same issue.

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Kristen Tran 2,120 Reputation points Independent Advisor

2026-10-01T11:20:13.9466667+00:00
Hi Andre,

Thank you for the update and for testing the suggested steps.

Based on the results you've shared, the fact that the same attachment can be opened successfully when the user connects through a different network suggests that the issue may be related to the connection path on the original network rather than the mailbox, PDF file, or browser itself. In some cases, a network may appear to be functioning normally while a proxy, firewall, TLS/SSL inspection service, web filtering solution, or DLP policy handles specific Microsoft 365 traffic differently.

Given this, I recommend working with your network or security team to perform a more targeted review while reproducing the issue. Specifically, they may want to:

Verify that the required Exchange Online and Microsoft 365 endpoints are reachable and are not being blocked or omitted from the network configuration.

Check whether SSL/TLS inspection, proxy authentication, content filtering, download scanning, or similar security controls are being applied to Outlook on the web traffic.

Compare the browser network requests captured on the affected network with those from a working network to identify any blocked requests, redirects, or HTTP errors.

For additional reference, please see:

Microsoft 365 URLs and IP address ranges

Microsoft 365 endpoints

These articles also explain that components such as firewalls, TLS inspection systems, packet inspection devices, and DLP services can affect Microsoft 365 connectivity and may require special handling for trusted Microsoft 365 traffic.

If the network and policy reviews do not reveal the cause, the next recommended step would be for your IT administrator to open a support request through Help & Support in the Microsoft 365 admin center. Microsoft Support can review the tenant-specific behavior and advise on any additional diagnostics that may be required. Instructions are available in:

Get support for Microsoft 365 for business

I hope this helps point the investigation in the right direction. If you have any questions or would like to share any findings from the network review, please let me know.

Kind regards.
Kristen Tran 2,120 Reputation points Independent Advisor

2026-10-02T09:29:06.71+00:00

Hi Andre,

Have you reviewed the provided answer? Please let me know if there are any updates.

Answer 3

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Answer 4

Harry Josh 0

The Outlook Web issue with users being unable to preview or download attachments sounds frustrating, especially if it affects multiple file types. It would be helpful to check whether the problem occurs across different browsers and accounts, and whether any recent Outlook or Microsoft 365 changes triggered it.

Kristen Tran 2,120 Reputation points Independent Advisor

2026-10-02T09:35:48.0566667+00:00

Hi Harry,

Thank you for sharing those additional troubleshooting suggestions.

If you're still experiencing the issue, I recommend working through the troubleshooting steps provided earlier in this thread, as they can help isolate whether the behavior is related to the browser, account, mailbox configuration, or a broader service issue.

If the problem persists after trying those steps, the next recommended action would be to open a support ticket with Microsoft Support so they can perform a more detailed investigation and review any service-side logs or configuration settings that are not available through the community forums.

I hope the information provided helps with your troubleshooting efforts. If you have any questions or updates to share, please feel free to let me know.

Kind regards.