Remote Desktop Errors and Fixes: 0x204, CredSSP, Black Screen, and More

• 13 November 2026
• Remote Desktop
• Written by Editorial Team

Most Remote Desktop errors come down to five causes: the client cannot reach port 3389, the two ends disagree on security (CredSSP), the account is not allowed in, licensing is not configured, or the graphics path fails after sign-in. Match your error message to the symptom table below, run the first fix for that symptom, and work through the steps in order. Most connection problems are solved by the fourth step or sooner.

Remote Desktop Protocol (RDP) is built into every Windows edition as a client and into most as a host, which makes it the default way to reach a remote Windows machine. It also means a small mismatch, such as a firewall rule, a missing patch, or an unset license mode, can lock you out with an error message that explains very little. This guide covers the six errors people search for most, with the cause, the fix, and the mistakes to avoid, plus a safe way to run RDP and a candid look at when it stops being worth managing yourself.

Apps4Rent runs remote desktops for a living, so these errors cross our desks all the time. The fixes below work whether you run your own server or use someone else’s.

Start Here: Match Your Symptom to the Fix

Find your error message in the table, then jump to the section that covers it.

What you see	Likely cause	First fix
“Remote Desktop can’t connect to the remote computer,” or error code 0x204	Host off or asleep, wrong name or IP, port 3389 blocked, or Remote Desktop disabled	Test port 3389 from the client
“An authentication error has occurred. The function requested is not supported.”	CredSSP patch mismatch between client and server	Update the unpatched side
Black screen after sign-in	Stuck session, display driver, bitmap cache, or UDP transport	Reconnect, then update the driver and test with UDP off
“Remote Desktop licensing mode is not configured”	No licensing mode or license server set on the session host	Set the mode and license server, then run the Diagnoser
“Your credentials did not work”	Wrong username format, missing group membership, or a logon-rights policy	Use COMPUTER\user or DOMAIN\user and check Remote Desktop Users
“The connection was denied because the user account is not authorized for remote login”	The account is not allowed to use Remote Desktop on that machine	Add the account to Remote Desktop Users

Before You Troubleshoot: The Five-Step Diagnosis

Random changes make RDP problems worse. Work through the checks in this order, and stop as soon as one of them finds the cause.

• Step 1: Is the host on and reachable? Confirm the machine is powered on, not asleep, and on the network. Try connecting by IP address instead of the name, which separates name-resolution problems from network problems.
• Step 2: Is port 3389 open? Test it from the client, not from the server. A server cannot tell you whether the path to it is blocked.
• Step 3: Is Remote Desktop enabled? Check the setting, the Remote Desktop Services service, and the firewall rule on the host.
• Step 4: Is the account allowed? Check group membership, the logon-rights policy, Network Level Authentication, and the username format.
• Step 5: Are patches, licenses, and graphics healthy? Check for CredSSP mismatches, an unset licensing mode, and display driver problems.

Three quick facts save a lot of time. First, Windows 10 and 11 Home can connect to other machines but cannot accept incoming Remote Desktop connections, so a Home PC will never be a valid target. Pro, Enterprise, Education, and Server editions can. Second, try a second device or network if you can. If another PC connects fine, the problem is your client or your network, not the host. Third, know which client you are using. The built-in Remote Desktop Connection app (mstsc) handles direct RDP and Remote Desktop Services deployments, while Microsoft’s Windows App is the newer client for Windows 365 and Azure Virtual Desktop. At the time of writing, Microsoft recommends the Remote Desktop app on Windows for connecting to Remote Desktop Services.

Error 0x204 and “Remote Desktop Can’t Connect to the Remote Computer”

What it means: the client could not establish a connection to the host. The message usually lists three reasons: remote access is not enabled on the host, the host is turned off, or the host is not available on the network. In practice, it is almost always one of these: the machine is unreachable, port 3389 is blocked somewhere along the path, or Remote Desktop is switched off.

Fix it in order

• Test the port from the client. In PowerShell, run Test-NetConnection -ComputerName <server-or-IP> -Port 3389 -InformationLevel Detailed. If TcpTestSucceeded is False, the problem is the network path, the firewall, or the listener. If it is True, skip ahead to the account and authentication sections, because the connection is reaching the host.
• Confirm Remote Desktop is enabled. On Windows 10 or 11 Pro and above, use Settings, then System, then Remote Desktop. On Windows Server, use Server Manager. Policy can also block it: the registry value fDenyTSConnections under HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server is 0 when connections are allowed and 1 when they are denied.
• Check the firewall rules. The Remote Desktop rule group, including “Remote Desktop – User Mode (TCP-In)” and its UDP twin, must be enabled for the network profile in use. In an elevated PowerShell window, Enable-NetFirewallRule -DisplayGroup "Remote Desktop" turns the built-in rules on. A network set to Public is a common reason they do not apply.
• Check that something is listening. On the host, netstat -anob | findstr 3389 shows whether anything holds the port, and tasklist /svc | findstr TermService shows whether the Remote Desktop Services process is running. If another process owns port 3389, stop it and restart the service.
• Check for a custom port. The listening port is stored under HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp as PortNumber, and 3389 appears as 0x00000d3d. If someone changed it, connect using the format server:port.
• Check everything between you and the host. For a cloud server, look at the cloud firewall or network security group. For an office machine, look at the router’s port forwarding and any VPN or firewall appliance that sits on the path.

A warning: do not “fix” this error by opening port 3389 to the whole internet. Exposed RDP is one of the most attacked services there is. If you need remote access from outside the network, put it behind a VPN or a remote desktop gateway, and our guide to locking down remote desktop access lists the controls that matter. If you are weighing a VPN against a hosted desktop, we compare how VPNs and hosted desktops differ in detail.

CredSSP Encryption Oracle Remediation Error

What it looks like: “An authentication error has occurred. The function requested is not supported. Remote computer: <name>. This could be due to CredSSP encryption oracle remediation.”

What it means: this is a security mismatch, not a network problem. In 2018, Microsoft patched a flaw in CredSSP, the protocol RDP uses to pass credentials (CVE-2018-0886), and added a policy called Encryption Oracle Remediation. A patched client can refuse to talk to an unpatched server, or the policy on one side can be stricter than the other side allows. The connection reaches the host, then authentication fails.

The behavior follows a simple pattern:

Server	Client	Result with the default and stricter settings
Patched	Patched	Connects
Patched	Not patched	Connects at the Mitigated setting, blocked at Force updated clients
Not patched	Patched	Blocked at Mitigated and Force updated clients, allowed only at Vulnerable

The right fix: update the unpatched side

Install current Windows updates on whichever side is behind. It is almost always the server. Microsoft recommends running the policy at Force updated clients or Mitigated on both clients and servers. If you cannot update the server yet because you cannot connect to it, patch it through another route, such as a console or a different management tool, or connect once from a machine that has not been updated.

The temporary workaround, and its cost

When you must connect to an unpatched server in order to patch it, Microsoft documents lowering the client’s protection level. Open the policy at Computer Configuration, Administrative Templates, System, Credentials Delegation, Encryption Oracle Remediation, set it to Enabled, and set the protection level to Vulnerable. The registry equivalent is:

REG ADD HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System\CredSSP\Parameters\ /v AllowEncryptionOracle /t REG_DWORD /d 2

The values are 0 for Force updated clients, 1 for Mitigated, and 2 for Vulnerable. Any change requires a reboot. Treat this as a bridge: connect, install the updates on the server, then remove the registry value or set the policy back to Mitigated or Force updated clients. Leaving it at Vulnerable keeps you open to the attack the patch was written to stop.

Servers that have stopped receiving updates are where this mismatch usually lives. If yours are in that position, our Windows Server 2016 end-of-support plan covers how to decide between upgrading, bridging, and moving them.

Remote Desktop Black Screen After Login

What it looks like: the connection succeeds and you sign in, but the remote session shows only black, sometimes with a cursor, and sometimes after a long pause.

What it means: authentication and the network are fine. Something between the session and the screen is failing: a stuck earlier session, a display driver, a cached image, or the UDP transport. Work from the least invasive fix to the most.

• Wait, then reconnect. Give the session 20 to 30 seconds. If it stays black, press Ctrl+Alt+End (the in-session equivalent of Ctrl+Alt+Delete). If Task Manager opens, use File, then Run new task, and start explorer.exe.
• Clear a stuck session. On the server, qwinsta lists sessions. A disconnected session that did not wake up properly can show black when you reconnect to it. Log it off with logoff <session ID> and connect again.
• Match the display settings. Mismatched resolutions and scaling between the client and the host are a common trigger. Connect full screen, or set a standard resolution, and try again. If you use several monitors, our multi-monitor setup guide covers the settings that matter.
• Update the display driver. Update the graphics driver on the host, and on the client if you can. On a virtual machine or VPS, check the virtual display adapter under Device Manager.
• Disable persistent bitmap caching. In Remote Desktop Connection, choose Show Options, open the Experience tab, and clear the persistent bitmap caching option. Delete the local cache folder under %LocalAppData%\Microsoft\Terminal Server Client\Cache if the problem returns.
• Turn off UDP on the client. Under Computer Configuration, Administrative Templates, Windows Components, Remote Desktop Services, Remote Desktop Connection Client, enable “Turn off UDP on Client” so RDP falls back to TCP. Restart the client afterward.
• Last resort: the WDDM policy. On the host, under Computer Configuration, Administrative Templates, Windows Components, Remote Desktop Services, Remote Desktop Session Host, Remote Session Environment, set “Use WDDM graphics display driver for Remote Desktop Connections” to Disabled, then reboot. This forces an older display driver model that avoids rendering failures, and it can reduce graphics performance, so test it before rolling it out widely.

If the machine does graphics-heavy work, a standard driver path may simply not have enough power. Our explanation of when you actually need GPU-enabled virtual desktops helps separate a configuration bug from a resource limit.

“Remote Desktop Licensing Mode Is Not Configured”

What it looks like: a pop-up when you sign in to a Remote Desktop Session Host: “Remote Desktop licensing mode is not configured. Remote Desktop Services will stop working in X days.” Past the deadline, the message changes to say it will stop working because the computer is past its licensing grace period.

What it means: a new Remote Desktop Session Host gets a 120-day grace period by default. If the licensing mode is not properly configured, or the host cannot reach a license server, you get this warning on every sign-in. It is a countdown, not a glitch, and when it reaches zero new connections stop.

Fix it in order

• Make sure a license server exists and is activated. Install the Remote Desktop Licensing role, or use an existing license server, activate it, and load your client access licenses (CALs).
• Set the licensing mode and the license server. In Server Manager on the RD Connection Broker, or in Group Policy under Computer Configuration, Administrative Templates, Windows Components, Remote Desktop Services, Remote Desktop Session Host, Licensing, enable both “Use the specified Remote Desktop license servers” and “Set the Remote Desktop licensing mode.” Choose Per User or Per Device to match the CALs you bought.
• Match the mode to the accounts. A frequent cause is Per User mode on a host where people connect with local accounts. Per User licensing depends on directory accounts, so local-account environments usually need Per Device CALs.
• Confirm the host can reach the license server. A host that cannot communicate with the license server produces the same warning even when everything else is correct.
• Verify with the Diagnoser. Open Server Manager, then Tools, then Remote Desktop Services, then RD Licensing Diagnoser. It reports the mode, the license server, and any problem it finds.

Resetting the grace period only delays the problem, so treat it as a stopgap and not a fix. For a plain-English explanation of why licensing trips people up and how the pieces connect, see our guide to how Remote Desktop Services and its licenses fit together.

“Your Credentials Did Not Work”

What it looks like: you type a username and password you know are right, and Remote Desktop rejects them.

What it means: the remote machine did not accept the identity you presented. It is usually how you entered the name, not the password itself.

• Use the right username format. For a local account, enter ComputerName\UserName. For a domain account, enter DomainName\UserName. For a Microsoft account, enter the account’s email address and its password.
• Use the password, not the PIN. A Windows Hello PIN or face sign-in is bound to the device where you set it up and does not work for a remote sign-in.
• Check Remote Desktop Users membership. By default, only administrators and members of the Remote Desktop Users group can sign in remotely. Add the account in Settings, then System, then Remote Desktop, or run Add-LocalGroupMember -Group "Remote Desktop Users" -Member "DOMAIN\username" in elevated PowerShell.
• Check the logon-rights policy. In Local Security Policy, under User Rights Assignment, “Allow log on through Remote Desktop Services” must include the user or a group they belong to. “Deny log on through Remote Desktop Services” overrides Allow, so look for the account there as well.
• Clear saved credentials. Remove the old entry for the host in Windows Credential Manager, especially after a password change.
• Check the account itself. A locked, disabled, or expired account fails in the same way, so confirm its status with whoever manages the directory.

If the message says the account “is not authorized for remote login,” the cause is almost certainly group membership or the logon-rights policy above. As a diagnostic only, you can temporarily turn off Network Level Authentication on the host to see whether the failure is authentication-related. Turn it back on immediately afterward, because NLA protects the host before a session is even created.

Other Common Remote Desktop Problems

A few more errors turn up often enough to be worth a short fix each:

• “An internal error has occurred.” A corrupted or mismatched Remote Desktop certificate is a common cause. On the host, open the Certificates snap-in for the computer account, delete the self-signed certificate under Remote Desktop, and restart Remote Desktop Services so it is recreated.
• Frequent disconnects. Check network stability first, then try switching off UDP on the client to force TCP, and review any session time limits set by policy on the host.
• Clipboard or file copy stops working. End and restart rdpclip.exe inside the session, then confirm clipboard and drive redirection are not blocked by policy.
• Printers do not appear. Printer redirection is controlled by policy and by the client’s local resources setting, so check both, and confirm the printer driver is available on the host.

When the Message Is Not Enough: Read the Logs

Remote Desktop error messages are short on detail, but Windows usually records more than it shows you. Two places are worth knowing, and both are on the host.

In Event Viewer, open Applications and Services Logs, Microsoft, Windows and look at the Operational logs for TerminalServices-RemoteConnectionManager, TerminalServices-LocalSessionManager, and RemoteDesktopServices-RdpCoreTS. Together they show connection attempts, session logons and disconnects, and transport problems with timestamps you can line up against the moment your connection failed.

For authentication failures, check the Security log for failed sign-in events and note the account name and the source address. A burst of failed attempts from addresses you do not recognize is not a configuration problem, it is a sign the host is exposed and being probed, and it is a reason to close direct access immediately. If the failures are one user and one address, you are back to the username format, group membership, and logon-rights checks above.

Command Cheat Sheet

These are the commands used above, collected in one place. Run the first group from the client and the rest on the host.

Command	What it tells you
Test-NetConnection -ComputerName <host> -Port 3389	Whether the client can reach the RDP port at all (run from the client)
netstat -anob | findstr 3389	Whether something is listening on port 3389 and which process owns it
tasklist /svc | findstr TermService	Whether the Remote Desktop Services process is running
Enable-NetFirewallRule -DisplayGroup "Remote Desktop"	Turns on the built-in Remote Desktop firewall rules
qwinsta	Lists sessions, including stuck or disconnected ones
logoff <session ID>	Ends a stuck session so a fresh one can start
gpupdate /force	Applies Group Policy changes without waiting for the next refresh

Fixing RDP Without Making It Less Safe

Every troubleshooting step has a tempting shortcut that makes the problem go away by weakening security. Resist them:

• Keep Network Level Authentication on. It makes users authenticate before a session is created. Turn it off only briefly to diagnose, then back on.
• Do not expose port 3389 to the internet. Use a VPN, a remote desktop gateway, or a brokered service, and require multi-factor authentication.
• Do not leave CredSSP at “Vulnerable.” Use it to get connected, patch, and put the setting back.
• Keep hosts patched. Unpatched remote access is a frequent way in, and patch mismatches are also the cause of the CredSSP error.
• Limit who can sign in. Use the Remote Desktop Users group deliberately, and review it when people leave.

For the broader picture of who is responsible for what in a remote-access setup, our guide to who secures what in the cloud explains where your duties start and your provider’s end.

When to Stop Fixing and Move to a Hosted Desktop

Fixing an RDP error once is routine. Fixing the same family of errors every quarter is a sign the setup costs more than it looks. Consider a hosted environment if any of these describe you:

• You are the only person who can fix it, and the errors tend to arrive on busy days.
• Licensing, patching, and certificates keep slipping because nobody owns them.
• Remote access is exposed or held together with firewall exceptions you do not fully trust.
• Several people need the same applications, and one server has become a single point of failure.

A hosted provider runs the platform, so licensing mode, firewall rules, patching, and backups stop being your tasks. Apps4Rent offers session-based remote desktops with licensing included for shared workloads, and fully managed desktops for each user when people need their own. The trade-off is less control over server-level settings, so confirm your applications are compatible before you move. If your errors are occasional and your setup is healthy, keep it. Hosting is for the cases where the upkeep has become the problem.

Common Mistakes When Troubleshooting RDP

• Changing several settings at once. When something finally works, you will not know which change did it, and you may have weakened security for no reason. Change one thing, test, and record it.

• Testing the port from the server. A server can see its own listener and still be unreachable. Always test from the client side of the connection.

• Switching off NLA and leaving it off. It removes a layer that protects the host before anyone signs in.

• Resetting the licensing grace period repeatedly. It hides the real problem and leaves you with a server that will stop accepting connections the day the reset stops working.

• Pasting registry fixes you do not understand. Many online fixes are written for a different Windows version or a different cause. Read what a setting does before you change it.

Frequently Asked Questions

1. What does RDP error code 0x204 mean?

   It means the Remote Desktop client could not establish a connection to the remote computer. The usual causes are a host that is off or unreachable, port 3389 blocked by a firewall or router, or Remote Desktop switched off on the host. Test the port from the client with Test-NetConnection to find which one applies.

2. Why does Remote Desktop say it can’t connect to the remote computer?

   Remote access may not be enabled on the host, the host may be turned off or asleep, or it may not be available on the network. A firewall blocking TCP port 3389 is the most common reason, so check the firewall rules, confirm the host is listening, and try connecting by IP address.

3. How do I check if port 3389 is open?

   From the client machine, run Test-NetConnection with the server name or IP and port 3389 in PowerShell. If TcpTestSucceeded is True, the port is reachable. If it is False, something on the network path, the host firewall, or the listener is blocking it.

4. What is the CredSSP encryption oracle remediation error and how do I fix it?

   It is an authentication error caused by a patch mismatch between the Remote Desktop client and server, related to a 2018 fix for CVE-2018-0886. The right fix is installing current Windows updates on the unpatched side, usually the server, and running the Encryption Oracle Remediation policy at Force updated clients or Mitigated.

5. Is it safe to set Encryption Oracle Remediation to Vulnerable?

   Only as a short-term bridge. Microsoft documents it as a workaround for connecting to an unpatched server, but it leaves you open to the attack the patch addresses. Use it to connect, patch the server, and then return the policy to Mitigated or Force updated clients. A reboot is required after any change.

6. Why does Remote Desktop show a black screen after login?

   Common causes are a stuck or disconnected session, a display driver problem, persistent bitmap caching, or the UDP transport. Reconnect, clear the stuck session, update the display driver, disable bitmap caching, and turn off UDP on the client before you try disabling the WDDM graphics policy on the host.

7. What does “Remote Desktop licensing mode is not configured” mean?

   The Remote Desktop Session Host has no licensing mode set, or it cannot reach a license server. New session hosts get a grace period, and the warning counts down until it ends. Set the licensing mode and license server, activate the license server, and check the result in the RD Licensing Diagnoser.

8. How long is the Remote Desktop grace period?

   A new Remote Desktop Session Host has a 120-day grace period by default. During that time users can connect without licenses being issued. After it ends, connections stop unless the licensing mode and license server are configured and licenses are available.

9. Why do my credentials not work for Remote Desktop?

   The most common cause is the username format: use ComputerName\UserName for a local account or DomainName\UserName for a domain account. Also check that the account is in the Remote Desktop Users group, that the logon-rights policy allows it, that you are typing a password and not a PIN, and that saved credentials are current.

10. Can Windows 10 or 11 Home accept Remote Desktop connections?

    No. Home editions can connect out to other machines but cannot host incoming Remote Desktop sessions. To accept connections you need Pro, Enterprise, or Education, or a Windows Server edition.

11. Should I disable Network Level Authentication to fix RDP errors?

    Only briefly, and only to diagnose an authentication problem. Network Level Authentication makes users authenticate before a session is created, which protects the host. If turning it off makes the connection work, fix the underlying cause, then turn it back on.

12. Is it safe to open port 3389 to the internet?

    No. Remote Desktop exposed directly to the internet is a frequent target for attackers. Put it behind a VPN or a remote desktop gateway, require multi-factor authentication, keep the host patched, and limit who is allowed to sign in.

Most Remote Desktop errors are less mysterious than their messages suggest. Start from the symptom, test one thing at a time, and resist the shortcut that trades security for a quick win.