Outlook Says 'The Attempt to Log On to Microsoft Exchange Has Failed' — How to Fix It

The "attempt to log on to Microsoft Exchange has failed" error in Microsoft Outlook prevents the application from connecting to an Exchange Server or Microsoft 365 mailbox. The error typically appears at Outlook startup and can be caused by expired passwords, MFA enforcement, autodiscover service failures, or licensing changes.

This guide covers every cause with step-by-step fixes.

Part 1. Understanding Why This Error Occurs

The error message "The attempt to log on to Microsoft Exchange has failed" appears when Outlook cannot authenticate with the Exchange server during the profile connection phase. Unlike a simple password error, this can have multiple root causes.

💡 Tip: Check whether the error appears at Outlook startup only, or also when opening or sending emails. Startup-only errors typically indicate an authentication or autodiscover issue. Errors during send/receive often indicate a network or server-side problem.

Part 2. Fix: Update Your Password

If your Exchange or Microsoft 365 password was recently changed — by you, an IT administrator, or an expiry policy — Outlook will fail to authenticate until the new credentials are provided.

Step 1 — Clear cached credentials in Windows Credential Manager:

1. Press Win + R → type control panel → press Enter
2. Go to Credential Manager → Windows Credentials
3. Find entries with MicrosoftOffice, MicrosoftExchange, or your Exchange server hostname
4. Click each entry → Remove
5. Restart Outlook — it will prompt for your new credentials

Step 2 — Enter credentials when prompted:

When Outlook prompts for a username and password:

• Username format: domain\username for on-premises Exchange, or user@company.com for Microsoft 365
• Check Remember my credentials to avoid repeated prompts
• Ensure Caps Lock is off

🗣️ r/sysadmin user: "The most common Exchange logon fail I see is cached credentials in Windows Credential Manager. People change their AD password and Outlook keeps trying the old one silently. Clean the credential manager first — solves it 70% of the time."

Part 3. Fix: Multi-Factor Authentication (Modern Authentication)

If your organization enforces Modern Authentication (MFA), older Outlook versions that use Basic Authentication cannot connect. Microsoft 365 disabled Basic Authentication for Exchange Online in October 2022.

Check your Outlook version:

1. Open Outlook → File → Office Account → About Outlook
2. Modern Authentication requires Outlook 2016 (build 16.0.7967 or later), Outlook 2019, Outlook 2021, or Microsoft 365 Apps

Enable Modern Authentication in Outlook 2016 via registry:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Common\Identity]
"EnableADAL"=dword:00000001
"Version"=dword:00000001

Save as a .reg file and double-click to apply, then restart Outlook.

If MFA prompts but does not complete:

1. Ensure your Authenticator app is current and approved
2. Try signing in through outlook.office365.com in a browser to test the MFA flow
3. Contact your IT administrator if MFA is blocking access — they may need to reset your MFA registration

⚠️ Important: Never disable MFA on your own without IT approval — doing so violates most corporate security policies and may trigger security alerts. If MFA is causing Outlook failures, the correct path is to re-register your MFA method through your company's IT self-service portal.

Part 4. Fix: Autodiscover Configuration

Autodiscover is a service that tells Outlook where the Exchange server is located. If autodiscover is misconfigured, Outlook cannot find the server to authenticate against.

Test autodiscover:

1. In Outlook, hold Ctrl and right-click the Outlook icon in the system tray
2. Select Test Email AutoConfiguration
3. Enter your email address and password → click Test
4. Review the Results tab — a successful autodiscover shows the Exchange server address and EWS URL

Common autodiscover fixes:

• DNS SRV record missing: Your IT administrator needs to create a _autodiscover._tcp.domain.com SRV record pointing to the Exchange server
• SSL certificate mismatch: The Exchange server's SSL certificate CN must match the autodiscover URL — contact IT to verify
• Manually configure Exchange server: In Outlook account settings, manually enter the Exchange server address if autodiscover fails persistently

Manual Exchange server configuration:

1. Go to File → Account Settings → select your Exchange account → Change
2. Click More Settings → Connection → Exchange Proxy Settings
3. Enter the Exchange server FQDN and check On fast networks, connect using HTTP first

💡 Tip: The Microsoft Remote Connectivity Analyzer (testconnectivity.microsoft.com) can test autodiscover, MFA, and Exchange connectivity from outside your network — useful for diagnosing issues that only appear remotely.

🗣️ r/Office365 user: "AutoConfiguration test showed the autodiscover SRV record was pointing to the old Exchange server after a migration. Fixed the DNS record and Outlook connected immediately."

Part 5. Fix: Corrupt Outlook Profile

A corrupted Outlook profile can cause authentication failures even when credentials and server settings are correct.

Create a new Outlook profile:

1. Close Outlook completely
2. Open Control Panel → Mail (Microsoft Outlook) → Show Profiles
3. Click Add → name the new profile → follow the account setup wizard
4. In the Always use this profile dropdown, select your new profile
5. Open Outlook with the new profile and test the connection

If the new profile also fails: The issue is not the profile — it is credentials, MFA, or server-side. Continue with the troubleshooting steps above.

Part 6. Recovering PST Files If Mailbox Data Is at Risk

If the Exchange logon failure has left your Outlook PST or OST file inaccessible — or if a profile deletion accidentally removed local mail data — Ritridata can recover deleted PST files from your drive.

PST files are typically stored at:

• Windows 10/11: C:\Users\[Username]\Documents\Outlook Files\
• Older Windows: C:\Users\[Username]\AppData\Local\Microsoft\Outlook\

Recovering a deleted PST file:

1. Stop all write activity to the drive
2. Install Ritridata on a different drive
3. Run a Deep Scan — filter for .pst and .ost file types
4. Recover the files to a safe location
5. Open in Outlook via File → Open & Export → Open Outlook Data File

💡 Tip: Ritridata's free scan identifies recoverable PST files before any purchase. PST files are typically large (often 1–20 GB), making them good candidates for deep scan recovery since large files leave more contiguous data on disk.

FAQ

Q: What is the difference between the "Exchange log on failed" error and "Cannot connect to server"? "The attempt to log on to Microsoft Exchange has failed" is a specific authentication error — Outlook found the server but could not log in. "Cannot connect to server" indicates Outlook could not reach the server at all, typically due to network or DNS issues. The fixes are different for each.

Q: Does this error occur with Microsoft 365 or only on-premises Exchange? The error occurs with both. For Microsoft 365, it most often indicates a password change, MFA requirement, or expired session token. For on-premises Exchange, autodiscover misconfiguration and certificate issues are more common causes.

Q: Can I fix this error without IT support? In many cases, yes — clearing Windows Credential Manager, updating your Outlook version, or creating a new profile are all user-level fixes. However, autodiscover DNS fixes, MFA registration resets, and license restoration typically require IT administrator access.

Q: Why does Outlook keep asking for my password even after I enter it correctly? Repeated password prompts usually mean the credentials are being accepted momentarily but then rejected again — often because Windows Credential Manager is still sending old cached credentials. Clear all Outlook-related entries from Windows Credential Manager and allow Outlook to prompt fresh.

Q: How do I check if my Microsoft 365 license is still active? Sign in to portal.microsoft.com with your work account. Under your profile, check My Account → Subscriptions or ask your IT admin to verify your license assignment in the Microsoft 365 Admin Center.

Q: Is it safe to recreate the Outlook profile? Will I lose emails? If your email is hosted on Exchange or Microsoft 365, creating a new profile downloads your mailbox fresh from the server — no data is lost. If you have local PST files not connected to the server, back them up before creating a new profile.

References

• Microsoft Support — "The attempt to log on to Microsoft Exchange has failed" error
• Microsoft Docs — Modern Authentication for Office clients
• Microsoft Remote Connectivity Analyzer
• Microsoft Support — Credential Manager overview
• Ritridata — Data Recovery Software