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Outlook error 0x80040115: what it means and how to fix it

Short answer

Outlook error 0x80040115 (MAPI_E_NETWORK_ERROR) means classic Outlook for Windows lost its connection to the mail server during Send/Receive, so mail stays in the Outbox. It usually reads "We can't complete this because we can't contact the server right now." The fix that works most often: close Outlook, run ipconfig /flushdns in Command Prompt, then reopen Outlook and press F9.

What this message means

0x80040115 is the MAPI code MAPI_E_NETWORK_ERROR. Classic Outlook for Windows uses MAPI to talk to Exchange, Microsoft 365 and Outlook.com mailboxes. The code means a request to the server was cut off or never reached it. The message says the server is unavailable, but in most cases the server is fine. Your webmail in a browser usually still works. The problem is almost always on the PC: a stale DNS cache, a VPN or security tool getting in the way, a faulty add-in, a damaged offline mailbox file (.ost) or a broken Outlook profile. It typically appears as a Send/Receive error with messages stuck in the Outbox, and the status bar may keep switching between Connected and Disconnected.

Common causes

CauseHow to tell
Stale or corrupted DNS cache on the PCWebmail works in a browser and other apps are online, but Outlook fails, and its status bar keeps switching between Connected and Disconnected. This often starts after you change Wi-Fi networks, connect or disconnect a VPN, or wake the PC from sleep.
A real network problem, or a VPN, proxy or security suite blocking OutlookWebmail or other websites are slow or failing too, or the error only appears while a VPN is connected and goes away when you disconnect it.
A faulty third-party add-inSending and receiving work when Outlook is started with outlook.exe /safe, but fail again when it opens normally.
Damaged or very large offline mailbox file (.ost)Only one account is affected, folders stop updating or stay on "Updating this folder", Outlook is slow, and the problem survives a restart and a DNS flush. If you turn off Cached Exchange Mode and it starts sending, the local cache is the culprit.
Corrupted Outlook profile or damaged Office installationThe error still appears in safe mode and after rebuilding the .ost file. A brand new Outlook profile works (profile issue), or even a new profile fails (installation issue).

How to fix it

1. Check the connection and flush the DNS cache

Classic Outlook for Windows (Microsoft 365, 2024, 2021, 2019, 2016) on Windows 10 and 11

  1. Sign in to your mail in a browser (outlook.office.com for work or school, outlook.live.com for personal accounts). If that also fails, the problem is the network or the mail service, not Outlook.
  2. If you use a VPN, disconnect it and try Send/Receive again.
  3. Close Outlook.
  4. Click Start, type cmd and press Enter to open Command Prompt.
  5. Type ipconfig /flushdns and press Enter. You should see "Successfully flushed the DNS Resolver Cache."
  6. Reopen Outlook and press F9 (Send/Receive All Folders) to retry messages waiting in the Outbox.

2. Start Outlook in safe mode and disable add-ins

  1. Close Outlook, press Windows key + R, type outlook.exe /safe and click OK.
  2. Choose your profile if asked, then send a test email.
  3. If it sends, go to File > Options > Add-ins, set Manage to COM Add-ins and click Go.
  4. Clear the check boxes for all non-Microsoft add-ins and click OK.
  5. Restart Outlook normally. If the error is gone, turn the add-ins back on one at a time to find the faulty one.

3. Rebuild the offline mailbox file (.ost)

Microsoft 365, Exchange and Outlook.com accounts only. Do not delete .pst files (POP accounts), because they may hold the only copy of your mail.

  1. Close Outlook and check that OUTLOOK.EXE is no longer running in Task Manager.
  2. Press Windows key + R, type %localappdata%\Microsoft\Outlook and press Enter.
  3. Find the .ost file named after the affected email address and rename it, for example to you@example.com.ost.old.
  4. Reopen Outlook. It creates a new .ost file and downloads your mailbox again from the server.
  5. Wait for the sync to finish before judging the result. Large mailboxes can take a while.
  6. Note: unsent Outbox items and anything that never synced to the server live only in the old file.

4. Test with Cached Exchange Mode turned off

Microsoft 365, Exchange and Outlook.com accounts in classic Outlook for Windows

  1. Go to File > Account Settings > Account Settings.
  2. Select the affected account and click Change.
  3. Clear "Use Cached Exchange Mode to download email to an Outlook data file", then click Next and Done.
  4. Restart Outlook and try sending.
  5. If it works now, the local cache is at fault. Rebuild the .ost file (previous fix), then turn Cached Exchange Mode back on for better performance.

5. Create a new Outlook profile

  1. Close Outlook.
  2. Open Control Panel, set View by to Small icons, and open Mail (Microsoft Outlook).
  3. Click Show Profiles > Add, enter a name for the new profile and click OK.
  4. Enter your email address, sign in and finish the setup.
  5. Select "Always use this profile", pick the new profile from the list and click OK.
  6. Open Outlook and test. If it works, you can remove the old profile later from the same window.

6. Repair Microsoft Office

Windows 11: Settings > Apps > Installed apps. Windows 10: Settings > Apps > Apps & features.

  1. Close all Office apps.
  2. Windows 11: open Settings > Apps > Installed apps, click the three dots next to Microsoft 365 (or Microsoft Office) and choose Modify. Windows 10: open Settings > Apps > Apps & features, select Microsoft 365 and click Modify.
  3. Choose Quick Repair and click Repair.
  4. Restart the PC and test Outlook.
  5. If the error continues, run the repair again and choose Online Repair. This reinstalls Office, needs an internet connection and takes longer.

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Still not fixed?

If webmail also fails, the problem is on the server or network side. Work accounts should check Service health in the Microsoft 365 admin center, or ask IT to do it. Give IT the full error text, the time it happened, and whether webmail works. They can test the mailbox from outside your network with Microsoft Remote Connectivity Analyzer (testconnectivity.microsoft.com). If webmail works but every fix above failed, temporarily turn off third-party antivirus or firewall email scanning. You can also try the new Outlook for Windows (the toggle at the top right of classic Outlook), which connects differently and does not use this profile. Personal Outlook.com users can keep using webmail and contact Microsoft Support from outlook.live.com.

Questions people ask

What does 0x80040115 mean in Outlook?

It is MAPI_E_NETWORK_ERROR: Outlook's connection to the mail server dropped or couldn't be made during Send/Receive. The server itself is usually fine, and the cause is normally on the PC (DNS cache, VPN, add-in, .ost file or profile).

Will I lose my emails if I delete or rename the .ost file?

No, for Microsoft 365, Exchange and Outlook.com accounts. The .ost file is only a local copy, and Outlook downloads everything again from the server. Only items that never reached the server, such as unsent Outbox messages, stay behind in the old file. Never delete a .pst file this way.

Why does error 0x80040115 keep coming back?

It usually recurs when something keeps disrupting the connection: switching networks, a VPN reconnecting, or security software filtering Outlook traffic. If flushing DNS only helps for a few days, test without the VPN or security suite, then rebuild the .ost file or create a new profile.

My webmail works, so why does Outlook say it can't contact the server?

The browser and classic Outlook connect differently, so a local problem such as a stale DNS entry, a bad add-in or a damaged profile can break Outlook while webmail keeps working. That pattern points to the PC, not the mail service.

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

The 0x80040115 code comes from MAPI, which only classic Outlook for Windows uses. The new Outlook for Windows and Outlook for Mac show different connection errors, so this guide is for classic Outlook.

Sources

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