Microsoft 365 Outlook will not open

Gary Smith 20 Reputation points
2026-09-08T17:37:32.1933333+00:00

I have Windows 11 and Microsoft 365. When I try to open Outlook, the task bar show an outlook window that is colored in Red with a Exclamation mark but outlook will not open. After trying several times to open outlook, I finally received a message advising me that outlook would open after it found an updated version. So, I went to automatic updates, clicked on check for updates and was told all updates were up to date. What do I have to do to open Outlook?

Microsoft 365 and Office | Other
0 comments
Answer accepted by question author

AI answer

2026-09-08T17:37:49.64+00:00

Try these steps in order:

  1. Start Outlook in safe mode.
    • Press Windows key + R.
    • Type Outlook /safe and select OK.
    • In Choose Profiles, accept the default profile and select OK.
    • If prompted, enter the password.
    If Outlook opens in safe mode, the red Outlook icon with the exclamation mark indicates Outlook is not operating normally, and an add-in is the likely cause.
  2. Disable all COM add-ins if safe mode works.
    • In Outlook, go to File > Options > Add-ins.
    • At the bottom, confirm Manage shows COM Add-ins, then select Go.
    • Clear all selected add-in check boxes, then select OK.
    • Choose File > Exit.
    • Restart Outlook normally.
    If Outlook opens normally after that, re-enable add-ins one at a time to find the one causing the problem. Do not use Remove during this test; disable only.
  3. Reset the Navigation Pane.
    • Close Outlook.
    • Press Windows key + R.
    • Type Outlook.exe /resetnavpane and select OK.
    This removes Navigation Pane customizations that can block Outlook from opening.
  4. Create a new Outlook profile if safe mode does not work.
    • Create a new profile using Create an Outlook profile.
    • Restart Outlook.
    • In Choose Profile, select the new profile and choose OK.
    If Outlook starts with the new profile, the original profile is corrupted.
  5. Repair Microsoft 365.
    • Right-click Start.
    • In Windows 11, select Installed apps.
    • Select the Microsoft Office product and choose Modify.
    • For Click-to-Run, select Online Repair > Repair.
    • For MSI-based installs, select Repair > Continue.
    Note: this repairs the entire Office suite.
  6. Check whether another Outlook or Office process is stuck.
    • If Outlook appears hung, wait two or three minutes and check whether a background process finishes.
    • If Outlook is stuck at loading profile, open Task Manager, find Office processes under Processes, and use End task for each Office process listed.
    • Then restart Outlook.
  7. Install Windows and Office updates again after Outlook is working enough to open.
    • Microsoft recommends installing the latest Windows updates and the latest Microsoft 365 or Office updates because they can replace out-of-date files and fix known issues.

If Outlook opens in safe mode, focus on add-ins first. If it does not open in safe mode, the next best step is a new Outlook profile, then an Office repair.

References:

AI-generated content may be incorrect. Read our transparency notes for more information.

Was this answer helpful?

2 people found this answer helpful.

1 additional answer

Sort by: Most helpful
Most helpful Newest Oldest
  1. Gary Smith 20 Reputation points
    2026-09-08T17:59:20.1266667+00:00

    After a LONG attempt to find the answer to my question, the above information finally fixed the problem I had with Outlook

    Was this answer helpful?

Your answer

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