How to Fix Outlook ‘AutoDiscover Could Not Be Reached’ on Domain-Joined PC

When you start Outlook on a domain-joined PC, you may see the error message “AutoDiscover could not be reached.” This prevents Outlook from connecting to your Exchange or Microsoft 365 mailbox. The cause is usually a DNS misconfiguration, a firewall rule, or a corrupted Outlook profile. This article explains why the error occurs and provides step-by-step fixes to restore AutoDiscover functionality.

Why AutoDiscover Fails on Domain-Joined PCs

AutoDiscover is the Outlook service that automatically configures Exchange and Microsoft 365 mail profiles. When Outlook starts, it sends a request to autodiscover.domain.com or to the Autodiscover service on Microsoft 365 servers. On domain-joined PCs, the failure typically occurs for three reasons:

DNS resolution failure. The internal DNS server does not have the correct AutoDiscover CNAME record for your domain. Outlook queries autodiscover.yourdomain.com and gets no response or a wrong IP address.

Firewall or proxy blocking. A group policy or local firewall rule blocks HTTPS traffic to port 443 for autodiscover URLs. This is common when the organization uses a web proxy that requires authentication.

Corrupt Outlook profile or cached data. If the profile was created with incorrect server settings or the Autodiscover cache is corrupted, Outlook will reuse the bad configuration and fail.

How AutoDiscover Works on a Domain-Joined PC

Outlook checks for AutoDiscover in this order:

1. SCP lookup in Active Directory. For on-premises Exchange, Outlook queries Active Directory for a Service Connection Point object. If the domain controller returns a valid SCP, Outlook uses that URL.
2. HTTPS to autodiscover.domain.com. If no SCP is found, Outlook sends an HTTPS request to https://autodiscover.yourdomain.com/autodiscover/autodiscover.xml.
3. DNS SRV record lookup. Outlook queries _autodiscover._tcp.yourdomain.com for an SRV record. If found, it uses the host name and port from the record.
4. Redirection via HTTP 302. The server can redirect Outlook to a different AutoDiscover endpoint.

If any of these steps fails, Outlook displays the “AutoDiscover could not be reached” error. The fix depends on which step is failing.

Steps to Diagnose and Fix AutoDiscover Errors

Use the following methods in order. Each method addresses a specific failure point.

1. Run the Outlook AutoDiscover Test
   In Outlook, go to File > Options > Mail. Under the Accounts section, click Test AutoDiscover. Enter your email address and password. The test shows which URL Outlook attempted and the HTTP response code. A 200 response means success. A 401 or 404 indicates a URL or authentication issue.
2. Verify DNS from the Domain-Joined PC
   Open a Command Prompt as administrator. Run nslookup autodiscover.yourdomain.com. You should see a valid A or CNAME record pointing to your Exchange server or Microsoft 365. Run nslookup -type=SRV _autodiscover._tcp.yourdomain.com. If the SRV record exists, it must point to a host that listens on port 443. If neither record exists, contact your DNS administrator to add the correct CNAME record.
3. Check Proxy Settings in Windows
   Go to Settings > Network & Internet > Proxy. If “Use a proxy server” is enabled, add autodiscover.yourdomain.com and outlook.com to the exception list. Alternatively, disable the proxy temporarily to test. If the error disappears, the proxy is blocking AutoDiscover. Work with your IT team to configure the proxy to allow HTTPS traffic to autodiscover URLs.
4. Clear the AutoDiscover Cache in Outlook
   Close Outlook. Open the Registry Editor by pressing Windows + R, typing regedit, and pressing Enter. Navigate to HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover. Delete the Boot key and the Cache key. Restart Outlook. This forces Outlook to perform a fresh AutoDiscover lookup.
5. Force Outlook to Use HTTPS Only
   In the Registry Editor, navigate to HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover. Create a new DWORD (32-bit) value named AutoDiscoverExcludeSrvRecord. Set its value to 1. Create another DWORD named AutoDiscoverOnly and set it to 1. Restart Outlook. This tells Outlook to skip SRV lookups and use only HTTPS to autodiscover.yourdomain.com.

If You Use Microsoft 365 and a Hybrid Environment

In hybrid deployments, the on-premises Exchange server may redirect Outlook to Microsoft 365. If the redirection fails, check the Exchange Management Shell. Run Get-OrganizationConfig | fl AutoDiscoverServiceInternalUri. The URI should point to the on-premises AutoDiscover endpoint. If it is empty or wrong, set it with Set-OrganizationConfig -AutoDiscoverServiceInternalUri https://autodiscover.yourdomain.com/autodiscover/autodiscover.xml.

If Outlook Still Shows the AutoDiscover Error

Outlook Cannot Find the Autodiscover SCP in Active Directory

For on-premises Exchange, the SCP object must exist in Active Directory. Open ADSI Edit on a domain controller. Navigate to Configuration > Services > Microsoft Exchange > Your Organization > Administrative Groups > Your Group > Servers > Your Server > Protocols. Under Autodiscover, verify the SCP URL. If missing, run the Exchange Setup wizard and select “Add Autodiscover Domain.”

Outlook Prompts for Credentials Repeatedly

This indicates that AutoDiscover reaches the server but authentication fails. Open Control Panel > Credential Manager > Windows Credentials. Remove any credentials for MicrosoftOffice16_Data:ADAL: or Outlook. Restart Outlook and re-enter your password. If the issue persists, your account may require Modern Authentication. Enable it via the registry key HKEY_CURRENT_USER\Software\Microsoft\Exchange\AlwaysUseMSOAuthForAutodiscover with a DWORD value of 1.

Outlook Uses a Wrong Autodiscover URL from a Previous Profile

Delete the Outlook profile and create a new one. Go to Control Panel > Mail > Show Profiles. Select your profile and click Remove. Restart Outlook and enter your email address. Outlook will perform a fresh AutoDiscover lookup.

AutoDiscover Fix Methods: Comparison

Item	DNS Record Fix	Registry Cache Clear	Proxy Exception
Target issue	Missing or wrong DNS record	Corrupted AutoDiscover cache	Firewall or proxy blocking HTTPS
Tools required	Command Prompt, DNS admin access	Registry Editor	Windows Settings or Group Policy
Outlook restart needed	Yes	Yes	Yes
Permanent fix	Yes, if DNS record is corrected	Temporary, until cache rebuilds	Yes, if proxy rule is added
Complexity	Medium	Low	Medium

The DNS record fix is the most reliable for domain-joined PCs because it addresses the root cause. The registry cache clear is a quick test that helps confirm the issue is cache-related. The proxy exception is necessary when the organization uses an authenticated web proxy.

After applying the fix, run the Outlook AutoDiscover test again. A successful test shows a green checkmark and the server URL. If the test still fails, review the HTTP status code and check the Windows event log under Applications and Services Logs > Microsoft > Office > Alerts for more details.

You can now resolve the “AutoDiscover could not be reached” error on any domain-joined PC. Start with the DNS verification and the registry cache clear. If the problem persists, apply the proxy exception or the registry key to force HTTPS-only lookup. For hybrid environments, verify the SCP object in Active Directory. As an advanced step, use the Exchange Remote Connectivity Analyzer from a non-domain machine to test AutoDiscover from outside your network.