Microsoft: Outlook bug downloads ‘TokenFactoryIframe’ file on every visit

Written by admin

Microsoft’s Outlook is downloading a mysterious file called “TokenFactoryIframe” on macOS when users access the email service through the Safari browser. This issue has now been widely reported by users who have discovered the ‘TokenFactoryIframe’ file that Outlook downloaded with each visit.

Outlook downloads this mysterious file every few seconds or at least every time you visit Outlook on the Apple platform. According to our findings, this appears to be an issue caused by a faulty server-side update released for Outlook and has nothing to do with Safari or macOS.

Microsoft acknowledged the issue in a statement, but the company has not revealed what is causing the downloads. It is probably due to a flaw in the HTML of the Microsoft 365 platform, as iframe is a well-known element used on websites to host interactive content or videos.

Based on reports from Reddit, it appears the issue was first spotted on May 2, and it has been widely reported for the past two days.

Microsoft spokesperson said the problem is limited to Safari and users can switch to another browser to prevent it. However, we have received reports claiming that the issue may also affect Chrome and Firefox on Apple’s platforms.

What is TokenFactoryIFrame?

After a recent server-side update to, users noticed that a file called “TokenFactoryIFrame” started appearing in the download section of Safari. The email client reportedly downloads the file every few seconds and the zero-byte file makes the site unusable.

This is called an inline frame (iframe) and is an element used for websites. It basically tries to load another HTML page in the document. This method is commonly used for web ads, embedded videos, interactive content, online games, and many other features.

TokenFactoryIFrame Outlook Solution

Fortunately, the file is zero kilobytes in size and harmless, so you can manually delete it from the system without worrying about the consequences. There’s a catch, though: deleting it from the device’s storage isn’t effective because the file is downloaded again when you visit in Safari, which is the default browser.

A Microsoft spokesperson confirmed that the company is aware of an issue where Outlook forcibly downloads token factory iframe every time you visit Outlook in a Safari browser on MacBook.

“There is an ongoing issue with Outlook on the web through the Safari browser where users are constantly being prompted to download a file titled “TokenFactoryIframe”. At this point, the recommended course of action is to use an alternate browser said Microsoft officials.

How To Prevent Outlook From Downloading TokenFactoryIframe

To repair TokenFactoryIframe problem in Outlook, follow these steps:

  1. launch Safaribut do not sign in to Outlook.
  2. Go to the Preferences tab of the Safari menu on the top.
  3. Select Websites
  4. Select Downloads left General column.
  5. This shows a list of websites with download permissions. As long as the download permission for Outlook and Office is disabled, the browser will stop downloading files served by Outlook.
  6. Find and deny everything in the list of websites with download permissions Outlook and Office submissions.
  7. When you’re done, leave Preferences

While this fixes the iframe bug in the token factory in Outlook, it also prevents the browser from downloading all attachments.

Fortunately, though, you can switch to Chrome to avoid Outlook issues, but this solution may not work for everyone.

About the author


Leave a Comment