Outlook doesn't open

Bill Donald 0 Reputation points
2026-10-01T17:42:04.25+00:00

Hello all,

Over the last couple of weeks, every time I want to open Outlook, it won't open. I have to restart my computer, then it works. Once my computer goes to sleep, I try to open it, and once again, it doesn't respond, so I have to restart. It does this with both Classic and the new Outlook. Any ideas? Thank you.

Outlook | Windows | Classic Outlook for Windows | For home

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  1. torrey botelho 0 Reputation points
    2026-10-01T17:58:46.13+00:00

    I need to speak to someone please

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  2. John Jefferson Doyon 88,935 Reputation points Independent Advisor
    2026-10-01T20:04:25.72+00:00

    @John Jefferson Doyon thank you for the reply. No error messages. It just won’t open. No, does not show in the task manager. Usually when it wakes up. If I let it sit for 5+ hours or even until the next day, when I wake it, enter my PIN and click on Outlook and nothing. windows 11. OS Build 26300.9550 it did this about 6 months ago and then stopped for a few months but started back up a few weeks ago. I’m using the new Outlook as Outlook Classic doesn’t seem to have the same emails, which is another confusing part.

    Hi,

    Thanks. Your Windows build 26300.9550 is Windows 11 version 26H2. I also checked Microsoft's current known issues, and I don't see this specific Outlook-after-sleep issue listed for that build.

    Since Outlook does not appear in Task Manager when this happens, please try repairing the new Outlook app first:

    • Go to Settings > Apps > Installed apps.
    • Find "Outlook (new)".
    • Click the three dots > Advanced options.
    • Select "Repair".

    Also open Microsoft Store > Downloads and install any available updates for Outlook and other Microsoft Store components.

    After that, restart the PC and test it again after the computer has been asleep for several hours.

    If it still happens, please let me know:

    1. Under Settings > System > About, what does "System type" show: x64-based or ARM-based?
    2. In new Outlook, go to Settings > General > About Outlook. What version is installed?

    The emails being different in Classic Outlook is probably a separate issue. New and Classic Outlook can have different accounts configured, so we can check that after the launching issue is sorted out.

    Click "Add comment" to let me know.

    Thanks!

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  3. AI answer

    2026-10-01T17:42:18.2133333+00:00

    Try these in order:

    1. End any stuck Outlook or Office processes.
      • Right-click the taskbar and open Task Manager.
      • Under Processes, look for Microsoft Outlook and any other Office processes.
      • Select each one and choose End task.
      • Then try opening Outlook again.
    2. If new Outlook is the one hanging:
      • Right-click Start > Task Manager.
      • Select Microsoft Outlook > End task.
      • Reopen new Outlook.
      • If it still fails, uninstall and reinstall new Outlook for Windows from the Microsoft Store.
    3. If classic Outlook is the one hanging, start it in safe mode to check add-ins.
      • Press Windows key + R.
      • Type outlook.exe /safe and select OK.
      • If prompted, accept the default profile and sign in.
      • If Outlook opens, go to File > Options > Add-ins.
      • Set Manage to COM Add-ins > Go.
      • Clear all add-in check boxes and select OK.
      • Restart Outlook normally.
      • If it works, re-enable add-ins one at a time, restarting Outlook after each one, until the problem returns. That identifies the faulty add-in.
    4. Check whether Outlook is blocked by a hidden dialog box or a long-running action.
      • Press Alt+Tab and look for any Outlook confirmation window.
      • Also check the Outlook status bar to see whether it is processing a large move or delete operation.
    5. Install the latest Windows and Microsoft 365 updates.
      • Outlook issues such as freezing and not responding can be resolved by current updates.
    6. Repair Microsoft 365 / Office.
      • Close all Microsoft 365 apps.
      • Open Control Panel > Programs and Features.
      • Right-click the installed Microsoft Office entry and choose Change.
    7. If classic Outlook still will not start, create a new Outlook profile.
      • A corrupted profile can prevent Outlook from opening.
      • After creating the new profile, restart Outlook and select that profile in Choose Profile.
      • Warning: if removing an old profile later, back up data files first. Removing a profile deletes offline cached content.
    8. If classic Outlook opens but still behaves inconsistently, repair Outlook data files with scanpst.exe.
    9. If the issue is specifically that Outlook will not reopen after closing or after sleep, and Task Manager shows Office processes still running, ending those processes can allow Outlook to open again.
    AI-generated content may be incorrect. Read our transparency notes for more information.

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