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Outlook error 0x8004010F: data file cannot be accessed (fix)

Short answer

Error 0x8004010F means classic Outlook for Windows cannot open the default data file (.pst or .ost) that your profile uses for sending and receiving. The file is usually missing, moved or corrupt, or the profile itself is damaged. The fix that works most often, and the one Microsoft recommends, is to create a new Outlook profile in Control Panel > Mail and make it the default.

What this message means

Classic Outlook for Windows keeps your mail in a data file on your computer. It uses a .pst file for POP and older IMAP accounts, and a .ost cache file for Microsoft 365, Exchange and Outlook.com accounts. Your profile marks one of these files as the default, and Send/Receive delivers mail into it. The 0x8004010F error appears during Send/Receive when Outlook cannot open that file at the path the profile has stored. Your mailbox on the server is usually fine. A common sign is that messages sit in the Outbox or new mail stops arriving, while the same account works normally in a web browser (Outlook on the web or Outlook.com).

Common causes

CauseHow to tell
The Outlook profile is corruptedEvery Send/Receive fails with 0x8004010F (sometimes shown as "The operation failed. An object could not be found"), the account works normally in the browser, and the problem often starts after a Windows or Office update.
The .pst file is stored in or was moved into a OneDrive-synced folderUnder File > Account Settings > Account Settings > Data Files, the path contains "OneDrive" (for example C:\Users\Name\OneDrive\Documents\Outlook Files). The error often begins right after you turn on OneDrive backup for Documents.
The default data file was moved, renamed or deletedOn the Data Files tab, the file marked with a check mark points to a folder that no longer exists, or Open File Location shows no file with that name.
A corrupted .ost file (Microsoft 365, Exchange or Outlook.com accounts)You can read older mail but new messages will not send or arrive, and creating a new profile alone does not fix it because the same damaged .ost is reused.
The data file is on a network drive or external diskThe data file path starts with \\server\ or a mapped drive letter, or with a USB drive that is not always connected. The error appears when the network or drive is unavailable.

How to fix it

1. Check where your default data file is

Classic Outlook for Windows (Microsoft 365, 2024, 2021, 2019, 2016). New Outlook for Windows and Outlook for Mac do not use this profile setup.

  1. In Outlook, go to File > Account Settings > Account Settings, then open the Data Files tab.
  2. Note the file with the check mark next to it. This is the default file that Outlook is failing to open.
  3. Select it and click Open File Location to confirm the file actually exists at that path.
  4. If the path contains OneDrive, a network share or a removable drive, go to the next fix. If the file is missing, go to the new profile fix.
  5. Close Account Settings.

2. Move the .pst file out of OneDrive or off a network drive

POP and IMAP accounts that use a .pst file, classic Outlook for Windows

  1. Close Outlook completely and wait for OneDrive to finish syncing.
  2. In File Explorer, copy the .pst file from the OneDrive or network folder to a local folder that OneDrive does not sync, for example C:\Outlook Files.
  3. Open Outlook. If it asks where the data file is, browse to the new local copy. Otherwise go to File > Account Settings > Account Settings > Data Files, click Add, and select the new copy.
  4. Select the new copy and click Set as Default, then remove the old OneDrive entry from the list.
  5. Click Send/Receive All Folders (F9) to test.

3. Create a new Outlook profile and make it the default

Classic Outlook for Windows on Windows 10 and Windows 11

  1. Close Outlook.
  2. Open Control Panel (search for it from Start), switch View by to Small icons, then open Mail (Microsoft Outlook).
  3. Click Show Profiles, then Add. Type a new profile name and click OK.
  4. Enter your email address and password and let Outlook set up the account, then click Finish. For a POP account whose mail lives in a .pst, choose Manually configure server settings, then Internet E-mail, and under Deliver new messages to select Existing Outlook Data File and browse to your .pst.
  5. Back in the Mail window, select Always use this profile, pick the new profile from the list, and click OK.
  6. Open Outlook and let the account sync. Microsoft 365, Exchange and IMAP accounts download mail from the server again.

4. Delete the damaged .ost file so Outlook rebuilds it

Microsoft 365, Exchange and Outlook.com accounts (mail is stored on the server)

  1. In the web version of your mailbox, confirm your mail is there. Anything that exists only in the .ost (for example unsent Outbox items) will be lost.
  2. Close Outlook.
  3. Press Windows key + R, type %localappdata%\Microsoft\Outlook and press Enter.
  4. Rename the .ost file for the affected account (for example add .old to the end) instead of deleting it right away.
  5. Open Outlook. It creates a new .ost and downloads your mailbox again, which can take a while on large mailboxes.
  6. If the error persists, repeat the new profile fix, then remove the old .ost.

5. Repair the .pst file with the Inbox Repair Tool (scanpst.exe)

POP and IMAP accounts with a .pst file. Paths shown are for Microsoft 365 and Outlook 2016 to 2024 Click-to-Run installs.

  1. Close Outlook.
  2. Open File Explorer and go to C:\Program Files\Microsoft Office\root\Office16 (on 32-bit Office: C:\Program Files (x86)\Microsoft Office\root\Office16).
  3. Double-click SCANPST.EXE.
  4. Click Browse, select the .pst file you found on the Data Files tab, then click Start.
  5. If errors are found, leave Make backup of scanned file before repairing selected and click Repair. Run it again until it reports no errors.
  6. Open Outlook and try Send/Receive.

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Still not fixed?

Sign in to your mailbox in a web browser (outlook.office.com for work or school accounts, outlook.com for personal accounts). If mail sends and arrives there, the problem is only in the desktop app, and a clean profile plus a deleted .ost almost always fixes it. If it fails in the browser too, the problem is on the server side: contact your email provider or IT admin. Before touching any .pst, back it up, because it may be the only copy of your POP mail. As a last resort, run Online Repair from Settings > Apps > Installed apps > Microsoft 365 > Modify.

Questions people ask

Will I lose my emails if I create a new Outlook profile?

Not for Microsoft 365, Exchange, Outlook.com or IMAP accounts, because that mail is stored on the server and downloads again. For POP accounts, attach your existing .pst file to the new profile (File > Open & Export > Open Outlook Data File) so your old mail comes with you.

Why can I receive email but not send new messages?

Outlook saves outgoing mail to the default data file before sending. If that file cannot be written, messages get stuck in the Outbox and Send/Receive reports 0x8004010F even though some incoming mail still appears.

Can I keep my Outlook .pst file in OneDrive?

Not while Outlook has it open. Microsoft does not support using a connected data file from a network or synced cloud folder, because constant writes cause sync conflicts and corruption. Keep active .pst files in a local folder and only back up copies to OneDrive with Outlook closed.

The error started after a Windows 11 update. Is the update to blame?

The update usually just exposes a profile that was already damaged. Microsoft's answer for this case is the same: create a new Outlook profile and set it as the default.

Does this error happen in the new Outlook or Outlook for Mac?

No. 0x8004010F comes from classic Outlook for Windows and its MAPI profile and .pst/.ost files. New Outlook for Windows and Outlook for Mac store data differently and show different errors.

Sources

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