If you’ve ever encountered Windows System Error Code ERROR_185, you know how frustrating it can be. This error usually pops up with the message:
"The domain already exists."
Whether you’re trying to join a domain, manage network resources, or perform system configurations, Error 185 can halt your progress. But don’t worry — in this detailed, easy-to-follow guide, I’ll walk you through step-by-step troubleshooting tips to quickly fix this error and get your system back on track.
What is Windows System Error Code ERROR_185?
Before diving into solutions, it’s helpful to understand the root cause. ERROR_185 means “The domain already exists.” This occurs when your computer or system service tries to create or join a domain that already exists in Active Directory or your network environment.
Common scenarios include:
- Joining a computer to a domain where the name is already registered
- Attempting to create a new domain with an existing name
- Network or Active Directory replication issues
- DNS conflicts related to domain names
Why Does ERROR 185 Happen?
Understanding why this error occurs can help you avoid future problems. Here are the frequent causes:
- Duplicate domain names: Two or more domains with the same name cause conflicts.
- Stale domain computer objects: Old records in Active Directory that have not been cleaned up.
- DNS misconfigurations: The domain name is unable to resolve or is mismatched.
- Permission issues: The account you use lacks sufficient rights to join or manage domains.
How to Fix Windows System Error Code ERROR_185 – Step by Step
Step 1: Confirm the Domain Name
Make sure the domain you are trying to join or create actually exists or doesn’t exist as you expect.
- Open Command Prompt on your Windows machine.
-
Type:
nslookup domainname.com
Replace domainname.com with your actual domain.
If the domain resolves to an IP address, it exists. If not, double-check your domain spelling or consult your network admin.
Step 2: Remove Stale Computer or Domain Objects from Active Directory
Old or duplicate computer objects can cause ERROR_185.
- Open Active Directory Users and Computers (ADUC) on your domain controller.
- In the Computers container or your organizational units (OUs), search for duplicate or old computer accounts.
- Right-click and delete any stale or duplicate entries.
- You might also want to clean up domain records in DNS under Forward Lookup Zones.
Tip: If you’re unsure, consult your AD admin because deleting records mistakenly might cause other issues.
Step 3: Flush DNS Cache and Reset Network Settings
DNS conflicts often cause domain name issues.
- Open Command Prompt as administrator.
-
Run the following commands in sequence:
ipconfig /flushdns
ipconfig /registerdns
net stop dnscache
net start dnscache - Restart your computer afterward.
This ensures your DNS cache clears old records so domain names get resolved properly.
Step 4: Make Sure Your Account Has Proper Permissions
You need sufficient rights to join or create domains.
- If you’re an end user, verify with your IT admin that your account has the “Add workstations to domain” permission.
- Domain joining typically requires Domain Admin or delegated rights.
Unauthorized attempts trigger ERROR_185 as Windows can’t override the existing domain.
Step 5: Remove the Computer from the Domain and Rejoin
If your computer thinks it’s already joined to a domain (or there’s a ghost entry), try removing and rejoining.
- Right-click This PC → Properties → Advanced system settings.
- Click Computer Name tab → Change.
- Select Workgroup and enter a simple name like
WORKGROUP. - Restart your PC.
- Then repeat the process to join the domain again with correct credentials.
Step 6: Use the Command Line to Remove Domain Membership
If GUI doesn’t work, try this command:
-
Open Command Prompt as admin and type:
netdom remove %computername% /domain:domainname
Replace domainname with your actual domain name.
Restart the system afterwards, then run:
netdom join %computername% /domain:domainname /UserD:domainadmin /PasswordD:*
Enter your Domain Admin credentials. This should rejoin the domain cleanly.
Step 7: Check Network and Firewall Settings
Sometimes the error happens due to blocked communication with the Domain Controller.
- Ensure ports such as TCP 88 (Kerberos), TCP/UDP 135, TCP 389 (LDAP), and TCP 445 (SMB) are open between your PC and Domain Controller.
- Temporarily disable firewall or third-party antivirus software to troubleshoot.
- Make sure the DC is reachable by pinging its IP.
Final Thoughts: Preventing ERROR_185 in the Future
After resolving the error, keep these tips in mind:
- Always check domain and computer names before joining or creating new domains.
- Regularly clean up old Active Directory records.
- Maintain DNS health and perform routine flushes.
- Use proper accounts with sufficient permissions.
- Communicate with your IT team about domain changes.
Conclusion
Facing the Windows System Error Code ERROR_185 can interrupt your workflow, but now you have a clear path to fix it — from verifying domain presence to cleaning AD and resetting network settings. Take it one step at a time, and your system will be domain-joined and stable in no time.
If you found this guide helpful, please share it with others who might be struggling with the same error. Your breakthrough is just a few clicks away!
Keywords: fix ERROR_185, Windows error 185, domain already exists error, Windows domain join error, Active Directory error fix, network error 185, Windows system error codes
If you have specific questions while working through this guide, feel free to ask!
