Outlook will not launch

Question

Yesterday my system crashed. I ended up performing a system restore for Windows 11. Then I reinstalled all my Microsoft 365 apps. I also reinstalled Outlook Classic which I was running previously before the system crash. Once Outlook was running it began to sync my email back, which it appeared to complete without any issues. However, the Calendar data did not return. I have been attempting to figure out how to get the Calendar working again without success. Now there seems to be a new problem, in that when I attempt to launch Outlook it wants an "Outlook Data File Password" which I do not have, and I do not believe I ever assigned this password when everything was originally installed on my PC. Now it will not launch and I cannot even see the email message that I could see a few hours ago. Any ideas what is happening? By the way, I am not a computer geek, so I am in the dark on what I actually need to do to fix this issue. Thank you.

Answer 1

Hi KB,

I understand that Outlook is now asking for an “Outlook Data File Password” after the Windows restore and Microsoft 365 reinstall. The Q&A Assist answer provides valid troubleshooting steps for classic Outlook startup issues, so please try those first if you have not had a chance to do so yet. I would just like to add one important clarification.

This password prompt is usually different from your Microsoft account password. In classic Outlook, an “Outlook Data File Password” normally refers to a local Outlook Data File, such as a .pst file. Microsoft’s support article explains that if a password was set on a .pst file and then forgotten, Microsoft cannot retrieve that password. It also notes that Offline Outlook Data Files .ost do not use this type of password. Reference: My Outlook Data File (.pst) password doesn’t work - Microsoft Support  

Because of that, if the missing calendar data was stored only in an old local .pst file, Outlook may continue asking for that data file password before it can open that file. If the calendar was stored on the mail server, creating a new Outlook profile should allow Outlook to sync it again from the server after the account is added.

For reference, these Microsoft articles may help confirm the next step:

• Change the password for an Outlook Data File (.pst)
• Repair Outlook Data Files (.pst and .ost)
• I can’t start Microsoft Outlook or receive the error “Cannot start Microsoft Outlook”

Please let me know whether Outlook opens when using a newly created profile. That will help confirm whether the issue is with the old profile or with the old local data file.

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Answer 2

The most likely cause is a problem with the existing Outlook profile or its data file after the crash and restore. Use the supported recovery steps in this order:

1. Start Outlook in Safe Mode
   1. Close Outlook.
   2. Press Windows key + R.
   3. Type: Outlook /safe
   4. Select the default profile if prompted and continue.
   5. If Outlook opens in Safe Mode, the issue is likely with add-ins or the profile. Disable add-ins as described in the referenced article and then restart Outlook normally.
2. Create a new Outlook profile If Outlook still will not launch or continues to prompt for a data file password, create a fresh profile and connect it to the account so mail and calendar can resync from the server.
   1. Close Outlook.
   2. Open Control Panel.
   3. Select User Accounts > Mail.
   4. Select Show Profiles.
   5. Select the existing profile and choose Remove only if sure data is backed up or stored on the server (removing a profile removes associated data files on that machine).
   6. Select Add.
   7. Enter a profile name.
   8. Enter the user name and primary email address (SMTP address), then select Next and complete setup.
   9. When finished, select Finish and then start Outlook with the new profile selected.
   If Outlook starts and syncs successfully with the new profile, the previous profile or its data file was corrupted and can be discarded once all needed data is confirmed present.
3. Repair Outlook data files if needed If there is a local Outlook Data File (.pst or .ost) that might be corrupted, run the Inbox Repair Tool (scanpst.exe) as described in the referenced documentation to repair it, then reopen Outlook.
4. Repair Office if Outlook still crashes or will not respond If Outlook continues to crash or hang even with a new profile:
   1. Open Control Panel.
   2. Select Uninstall a program.
   3. Right-click the Microsoft 365 installation.
   4. Select Change > Online Repair and complete the repair.
   5. Restart the computer and try Outlook again.

If none of these steps restore access, use Outlook on the web or the new Outlook for Windows as a temporary workaround while contacting Microsoft Support for further assistance, especially if the issue matches a known service incident.

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References:

• I can’t start Microsoft Outlook or receive the error “Cannot start Microsoft Outlook. Cannot open the Outlook Window”
• Outlook for Windows not responding, hangs, freezes, or stops working
• Outlook crashes or stops responding when used with Office 365