Share via

Firefox Browser Prompts for Office 365 Login When Opening PDFs from SharePoint Online

Nisk 30 Reputation points
2025-03-24T04:37:14.9933333+00:00

A user is experiencing issues with Firefox browser, where it prompts for login to their Office 365 account when attempting to open PDF files from SharePoint Online. This functionality works correctly in Chrome and Edge.

Is this a known issue with Firefox?

SharePoint Development
SharePoint Development
SharePoint: A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.Development: The process of researching, productizing, and refining new or existing technologies.
3,572 questions
0 comments

2 answers

Sort by: Most helpful
Most helpful Newest Oldest
  1. Ling Zhou_MSFT 23,605 Reputation points Microsoft External Staff
    2025-03-24T07:16:02.0866667+00:00

    Hi @Nisk,

    Thanks for reaching out to us. We are very pleased to support you.

    Yes, this issue with Firefox prompting for login when trying to open PDF files from SharePoint Online is a known behavior, often linked to how Firefox handles cookies and authentication for certain websites. Specifically, Firefox may have issues with session cookies or cross-site tracking that prevent it from maintaining a seamless authentication flow with Microsoft 365 services like SharePoint.

    Here are a few potential reasons and solutions:

    1. Firefox has enhanced privacy settings that block third-party cookies by default. SharePoint Online and other Microsoft services often use these cookies to maintain your authentication session. If these cookies are blocked, Firefox won't be able to keep the user logged in, prompting the login page when trying to open PDFs. Solution:
      • In Firefox settings, navigate to Privacy & Security.
      • Under Enhanced Tracking Protection, select Standard instead of Strict, or you can add SharePoint domains to the exceptions list.
    2. Ensure that the Firefox browser is updated to the latest version. Sometimes these issues are fixed in newer releases of the browser.
      • Go to Help > About Firefox and check for updates.
    3. Select the Open in Browser option instead of double-clicking the file to open it. Please try if the problem persists with this approach. User's image
    4. Try to use browser's InPrivate mode to see if the same error occurs.

    If you have any questions, please do not hesitate to contact me.

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. It will be beneficial to more community members reading here. Your contribution will be highly appreciated.

  2. Nisk 30 Reputation points
    2025-03-28T02:39:28.95+00:00

    thank you for the advise

    0 comments

Your answer

Answers can be marked as Accepted Answers by the question author, which helps users to know the answer solved the author's problem.