Fixes / Outlook · Checked

Outlook stuck on "Trying to connect...": causes and fixes

Short answer

"Trying to connect..." in the status bar of classic Outlook for Windows means Outlook can't reach or sign in to your Exchange or Microsoft 365 mailbox, so no mail is sent or received. Most often the cause is an expired or cached sign-in token. Close every Office app, clear the saved Office credentials, restart Windows and sign in again when Outlook asks.

What this message means

The status bar at the bottom right of classic Outlook shows the state of the connection to your mail server. "Connected to: Microsoft Exchange" means it is working. "Trying to connect..." means Outlook keeps trying to open a session with Exchange Online or your company's Exchange server and never finishes. Usually a sign-in (authentication) step is failing, the network is blocking the connection, or the Outlook profile is damaged. Mail you already downloaded is still readable because Outlook keeps a local copy (the .ost file). New messages won't arrive, and anything you send waits in the Outbox until the connection comes back.

Common causes

CauseHow to tell
Expired or corrupted cached sign-in (modern authentication token)Outlook on the web (outlook.office.com) works with the same account, but the desktop app stays on "Trying to connect...". Restarting the PC fixes it for a day or two, then it comes back. Sometimes a sign-in window flashes and closes, or never appears.
Outlook is set to Work Offline, or the network is downThe status bar says "Working Offline" or switches between that and "Trying to connect...", and the Work Offline button on the Send / Receive tab looks pressed. Or other websites don't load either.
VPN, proxy, firewall or network-management software getting in the wayThe problem starts when you join a VPN, go on office Wi-Fi, or after a Dell Optimizer or ExpressConnect update. On a phone hotspot with the VPN off, Outlook connects.
Account mismatch between Windows and the mailboxYou signed in to Windows with a different Microsoft or work account than your mailbox, or the profile has more than one mailbox. The mailbox that doesn't match your Windows account is the one that stays disconnected.
Damaged Outlook profile or outdated Office buildRestarting and signing in again don't help. A new Outlook profile connects right away, or the problem started right after an Office update.
Microsoft 365 service outageSeveral people in your organization lose Outlook at the same time, and Outlook on the web is slow or fails too.

How to fix it

1. Check Work Offline and your connection, then restart

Classic Outlook for Windows (Microsoft 365, Outlook 2021, 2019, 2016)

  1. In Outlook, open the Send / Receive tab. If Work Offline is highlighted, click it once to turn it off.
  2. Open a website in your browser to confirm the internet works.
  3. Disconnect any VPN or proxy for now. If you can, test on another network such as a phone hotspot.
  4. Sign in at outlook.office.com with the same account. If that also fails, the problem is the account or the service, not your PC.
  5. Close Outlook, restart Windows (a full restart, not sleep) and open Outlook again.

2. Clear saved Office sign-ins and sign in again

Classic Outlook for Windows 10 and Windows 11 with a Microsoft 365 or Exchange Online account

  1. Close Outlook, Teams, Word and every other Office app. In Task Manager (Ctrl+Shift+Esc), end any leftover OUTLOOK.EXE process.
  2. Press Windows+R, type %localappdata%\Microsoft and press Enter.
  3. Move the OneAuth and IdentityCache folders to your desktop (move them rather than deleting them, so you can put them back).
  4. Open Credential Manager from the Start menu, choose Windows Credentials, and remove the entries that start with MicrosoftOffice16_Data.
  5. Restart Windows, open Outlook and sign in when asked. Once the status bar says Connected, you can delete the folders you moved.

3. Create a new Outlook profile

Classic Outlook for Windows

  1. Close Outlook.
  2. Open Control Panel, set View by to Large icons and open Mail (Microsoft Outlook). You can also go to File > Account Settings > Manage Profiles in Outlook.
  3. Click Show Profiles, then Add, and enter a new name, such as Outlook2.
  4. Enter your email address and finish the setup.
  5. Choose Always use this profile, select the new profile and click OK.
  6. Open Outlook and wait for it to download your mailbox. Once it works, you can remove the old profile.

4. Update Office and Windows

  1. In Outlook, go to File > Office Account > Update Options > Update Now.
  2. Open Settings > Windows Update, install any pending updates and restart.
  3. If Outlook still won't connect, open Settings > Apps > Installed apps (Windows 11) or Apps & features (Windows 10), find Microsoft 365, click Modify and run Quick Repair, then Online Repair.

5. Remove Dell ExpressConnect or Dell Optimizer (Dell PCs)

Dell Latitude, Precision and other models with Dell Optimizer installed

  1. Open Settings > Apps > Installed apps (Windows 11) or Apps & features (Windows 10).
  2. Search for ExpressConnect. If you find it, uninstall it. If it isn't listed, uninstall Dell Optimizer.
  3. Restart Windows and open Outlook.
  4. If you want to keep Dell Optimizer, turn off Wi-Fi while you're plugged into a wired network, so the software doesn't keep switching adapters.

6. Reset the Windows connection settings or prefer IPv4 (advanced)

Windows 10 and Windows 11. Needs admin rights. Back up the registry first.

  1. Press Windows+R, type regedit and press Enter.
  2. Go to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections.
  3. Right-click the Connections key, choose Export to save a backup, then delete the DefaultConnectionSettings and SavedLegacySettings values. Windows recreates them.
  4. If the network has IPv6 problems, Microsoft's workaround is to create a DWORD named DisabledComponents with the value 0xFF under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters. A gentler option is to set Windows to prefer IPv4 over IPv6.
  5. Restart Windows and open Outlook.

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Still not fixed?

Hold Ctrl, right-click the Outlook icon in the system tray and choose Connection Status. Write down the server names and the status you see, and send them to IT. If you use a work or school account, your IT admin can check the Exchange Online entry in Microsoft 365 Service health and run the Outlook connectivity diagnostic in the Microsoft 365 admin center. To keep working in the meantime, use Outlook on the web (outlook.office.com) or switch on the New Outlook toggle at the top right of classic Outlook. New Outlook connects differently and often works when classic Outlook doesn't. If you're a home user, contact Microsoft Support from the Get Help app.

Questions people ask

Why does Outlook say "Trying to connect..." when my internet works?

In most cases your internet is fine and the Outlook sign-in to Exchange or Microsoft 365 is what's failing, usually because of an expired cached token. A VPN, a proxy or network software can also block it. Clearing the saved Office sign-ins and restarting fixes most cases.

Why does Outlook work after a restart but get stuck again a day later?

That pattern points to the sign-in token or network software, not the mailbox. Clear the OneAuth and IdentityCache folders and the MicrosoftOffice16 credentials. On Dell PCs, remove ExpressConnect or Dell Optimizer.

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

Not for Microsoft 365 or Exchange accounts. The mail lives on the server, and the new profile downloads it again. Only local .pst files need to be reopened with File > Open & Export > Open Outlook Data File.

Does switching to New Outlook fix "Trying to connect"?

It often does, because New Outlook connects through the same service as Outlook on the web. That makes it a good stopgap. It doesn't repair classic Outlook, though.

How do I check if Microsoft 365 is down?

Admins can open Service health in the Microsoft 365 admin center and look at Exchange Online. Other users can try outlook.office.com. If that fails too, the problem is probably on Microsoft's side or with your account.

Sources

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