A common concern for Windows Server administrators is what happens when users suddenly receive this Remote Desktop error:

“The remote session was disconnected because there are no Remote Desktop License Servers available to provide a license. Please contact the server administrator.”

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The immediate question is:

If this licensing error occurs, can at least one user still connect to the server?

The important answer is:

There is no guaranteed “one normal user will always be allowed” rule. Normal Remote Desktop Services (RDS) user sessions can be rejected when the RD Session Host cannot satisfy its licensing requirements. However, an administrator may still be able to access the server using an administrative Remote Desktop session, such as mstsc /admin, for server management and troubleshooting.

Existing sessions can also behave differently from new connection attempts. Therefore, seeing one person still connected does not mean RDS licensing is functioning correctly.

Understanding the RDS Licensing Error

In a multi-user Remote Desktop Services environment, the basic process is:

User
  ↓
Remote Desktop Connection
  ↓
RD Session Host
  ↓
RDS Licensing Check
  ↓
RD License Server
  ↓
Appropriate RDS CAL
  ↓
User Session

If the RD Session Host cannot use an appropriate licensing server, the process may instead become:

User
  ↓
RD Session Host
  ↓
Licensing required
  ↓
License Server unavailable / misconfigured
  ↓
License cannot be obtained
  ↓
Connection rejected

This does not automatically mean that the organization hasn't purchased RDS CALs.

The problem could be that the licensing server is unavailable, the Session Host isn't configured to use it, the licensing mode is incorrect, the licensing service is stopped, or the installed CALs aren't suitable for the deployment.

Is At Least One Normal User Guaranteed to Get RDP Access?

No.

Windows Server does not provide a general RDS licensing rule saying:

“When licensing fails, always allow one normal RDS user.”

An administrator therefore shouldn't design an emergency-access strategy around the assumption that one ordinary user will remain able to connect.

For example, imagine an RDS server normally has 20 concurrent users.

Normal condition:

User 1  → Connected
User 2  → Connected
User 3  → Connected
...
User 20 → Connected

A licensing problem occurs.

It would be incorrect to assume the resulting state must be:

User 1  → Allowed
Users 2–20 → Blocked

The actual behavior depends on the licensing problem, licensing mode, existing sessions, deployment configuration and whether a client/device already has relevant licensing state.

The safe assumption is:

Normal RDS user access may become unavailable.

Can an Administrator Still Access the Server?

This is the important distinction.

Windows Server supports Remote Desktop connections for remote administration, separately from deploying RD Session Host for ordinary multi-user application/desktop access.

An administrator troubleshooting an RDS licensing failure can try:

mstsc /admin

Press:

Win + R

Enter:

mstsc /admin

Then connect to:

SERVERNAME

or:

192.168.1.10

using appropriate administrative credentials.

The purpose is to gain administrative access to diagnose and repair the server.

It should not be used as a substitute for proper RDS licensing for ordinary employees.

Normal RDS Session vs Administrative Session

These two scenarios should not be confused.

This explains why an administrator might successfully access a server while employees receive the licensing error.

Can Existing Users Remain Connected?

Yes, this is possible.

Suppose 15 employees are already working:

09:00 AM

User01 → Connected
User02 → Connected
User03 → Connected
...
User15 → Connected

A licensing-related problem then develops.

At 11:00 AM:

Existing sessions
       ↓
May remain active

New User16
       ↓
Attempts RDP
       ↓
Licensing problem
       ↓
Connection rejected

Therefore, you might see several users actively working while another user gets:

No Remote Desktop License Servers
available to provide a license

That does not prove the licensing server is healthy.

What Happens If an Existing User Disconnects?

A disconnected session is different from a logged-off session.

For example:

User01
   ↓
Working session
   ↓
RDP window closed
   ↓
Session becomes Disconnected

The user's session may continue to exist on the server.

If the same user reconnects, Windows may attempt to reconnect them to that existing session.

But don't depend on this as an emergency-access method. Licensing configuration, session state and RDS infrastructure can affect reconnection behavior.

A full logoff is different:

User01
   ↓
Log Off
   ↓
Session terminated

The next login is a new session establishment attempt.

During a serious licensing failure, that new connection may fail.

Why Can One User Connect While Another Cannot?

This situation can occur for several reasons.

1. One user already has an active session

User A:

Session established before problem
→ Still working

User B:

New RDP connection
→ Licensing check
→ Failure

The apparent inconsistency is therefore related to session timing.

2. Per Device Licensing Can Produce Different Client Behavior

With Per Device RDS licensing, licensing is associated with the connecting device.

As a result, different client devices can have different licensing states.

Conceptually:

PC-A
Previously licensed
       ↓
May behave differently

PC-B
New device
       ↓
Needs licensing
       ↓
Licensing server unavailable
       ↓
Connection problem

Therefore, testing from one computer alone may not tell you the complete condition of the RDS deployment.

3. Administrator Is Using /admin

Another common scenario:

Employee
mstsc
   ↓
Licensing error

but:

Administrator
mstsc /admin
   ↓
Server accessible

This does not mean licensing has started working.

The administrator is connecting for server administration rather than testing a normal RDS workload session.

4. Licensing Server Became Unavailable After Sessions Were Created

Suppose:

8:00 AM
RD License Server → Working

8:30 AM
20 users connect successfully

10:00 AM
RD Licensing service/problem occurs

Existing sessions don't necessarily disappear simply because the licensing infrastructure later develops a problem.

At 10:30 AM:

Existing User01 → Working
Existing User02 → Working

New User21 → Connection error

This is one reason administrators sometimes receive reports such as:

“RDP is working for some people but not for others.”

Does the Error Immediately Disconnect Everyone?

Not necessarily.

The appearance of the licensing error for a new connection does not mean Windows must immediately terminate every session already running on the Session Host.

The problem may primarily become visible when another client attempts to establish a connection.

Therefore:

Existing session ≠ proof licensing is healthy

and:

Failed new connection ≠ every existing session must already be disconnected

What Happens After the RDS Grace Period Expires?

A newly deployed RD Session Host normally receives an initial licensing grace period.

During that period, users may be able to establish RDS sessions before the permanent RDS licensing infrastructure is fully configured.

The typical progression is:

RD Session Host installed
        ↓
Grace period
        ↓
RDS licensing should be configured
        ↓
Grace period expires
        ↓
Proper licensing required
        ↓
Licensing unavailable
        ↓
New normal RDS connections may fail

A common real-world situation is:

“The server worked perfectly for several months and suddenly everybody started getting an RDS license error.”

The administrator may believe a Windows Update caused the issue when the real problem is that the server was operating within its grace period and permanent RDS licensing was never correctly configured.

The Grace Period Is Not a Permanent Licensing Solution

Administrators should not attempt to operate production RDS environments by repeatedly manipulating the licensing grace period.

The correct architecture is:

Windows Server
+
RD Session Host
+
RD Licensing
+
Activated License Server
+
Appropriate RDS CALs
+
Correct Licensing Mode

The objective should be to repair the actual licensing problem.

What Should an Administrator Do When Nobody Can Connect Normally?

First, try administrative access.

From a Windows workstation:

mstsc /admin

Enter the server address and use authorized administrative credentials.

Once connected, investigate the RDS licensing configuration.

Step 1: Open RD Licensing Diagnoser

On the server:

Server Manager
→ Tools
→ Remote Desktop Services
→ RD Licensing Diagnoser

This is one of the most useful tools for this situation.

Check for messages involving:

Licensing mode isn't configured

No license server is available

License server cannot be contacted

No appropriate licenses available

Licensing configuration problem

Don't immediately start changing registry values before reading what the Diagnoser reports.

Step 2: Check Remote Desktop Licensing Manager

Run:

licmgr.exe

or open:

Server Manager
→ Tools
→ Remote Desktop Services
→ Remote Desktop Licensing Manager

Verify:

License Server
      ↓
Activated?

RDS CAL Pack
      ↓
Installed?

CAL Version
      ↓
Suitable?

Licensing Mode
      ↓
Correct?

A healthy configuration should broadly resemble:

RD Licensing Server
        ↓
Activated
        ↓
RDS CAL Pack Installed
        ↓
Correct CAL version/type

Step 3: Check Licensing Mode

Open:

gpedit.msc

Navigate to:

Computer Configuration
→ Administrative Templates
→ Windows Components
→ Remote Desktop Services
→ Remote Desktop Session Host
→ Licensing

Check:

Set the Remote Desktop licensing mode

The appropriate mode should be configured according to the organization's licensing:

Per User

or:

Per Device

Don't randomly switch between these modes merely to make the error disappear. The configuration needs to correspond to the RDS CAL model and deployment.

Step 4: Check the Specified License Server

In the same policy location, examine:

Use the specified Remote Desktop license servers

For example:

Enabled

License Server:
RDSLIC01.company.local

If the Session Host points to an old or nonexistent server, licensing can fail even though valid CALs exist elsewhere.

Step 5: Check the RD Licensing Service

Open:

services.msc

Locate:

Remote Desktop Licensing

Or use PowerShell:

Get-Service TermServLicensing

On the licensing server, confirm that the required licensing service is operational.

Step 6: Check Group Policy

Run:

gpresult /h C:\RDS-Policy.html

Open:

C:\RDS-Policy.html

Review Remote Desktop Services licensing policies.

This is important because an Active Directory GPO may be overriding a configuration that looks correct locally.

For example:

Administrator configures:

License Server = RDSLIC02

but domain GPO says:

License Server = RDSLIC01

The server can continue using the wrong configuration.

Step 7: Check Connectivity

When the Session Host and License Server are separate machines:

RDSHOST01
     ↓
Network
     ↓
RDSLIC01

Verify DNS and network communication.

For example:

Resolve-DnsName RDSLIC01

Successful ping alone isn't sufficient to prove the licensing service is reachable.

Check:

DNS
Firewall
RPC/service communication
Domain connectivity
Licensing service
Server availability

Should You Log Off Existing Users During the Problem?

Generally, avoid unnecessary logoffs until you understand the licensing failure.

Suppose:

20 normal users
15 currently connected
5 unable to connect

If those 15 active users are doing critical work, logging them off merely as a test can create additional disruption.

A better approach is:

Keep working sessions intact
        ↓
Use administrative access
        ↓
Diagnose licensing
        ↓
Correct configuration
        ↓
Test with controlled user
        ↓
Confirm new sessions work

A reboot should similarly not be the first troubleshooting action merely because users are still connected. A reboot terminates or disrupts existing sessions and doesn't fix incorrect licensing configuration by itself.

Practical Example

Consider a Windows Server running:

Windows Server 2022

25 RDS user accounts

18 users normally connected

RDS Per User CALs

Users suddenly report:

There are no Remote Desktop License Servers available to provide a license.

Current status might be:

User01 → Existing session → Working
User02 → Existing session → Working
User03 → Existing session → Working

User18 → New login → Error
User19 → New login → Error

Administrator → mstsc /admin → Accessible

This is entirely different from:

Server is down

The operating system may be functioning perfectly.

The problem can be specifically within the RDS licensing path.

Can We Assume One Administrator Will Always Be Able to Connect?

Even administrative RDP access shouldn't be your only recovery method.

A server can have other problems unrelated to RDS licensing:

Remote Desktop Services failure
Firewall issue
Network failure
Authentication problem
Server hung
Resource exhaustion
RDP disabled

Therefore, production servers should ideally have an alternative management route, such as virtualization console access or physical/local console access.

For example:

Normal RDP
      ↓
Fails

mstsc /admin
      ↓
Try administrative access

Still fails
      ↓
VM Console / Hypervisor Console
      ↓
Server administration

This prevents an RDP problem from becoming a complete server lockout.

Important Distinction: Windows Server Administrative RDP vs RDS

These concepts are frequently confused.

Remote administration

Used by administrators to manage Windows Server.

Administrator
      ↓
Remote Desktop
      ↓
Server administration

Remote Desktop Services

Used to provide Windows desktops/applications to multiple users.

Employee 1 ─┐
Employee 2 ─┤
Employee 3 ─┤
Employee 4 ─┤
             ↓
       RD Session Host
             ↓
       Business Apps

Examples include users running:

Accounting software
ERP software
Microsoft Office
Browsers
Business applications

The latter is an RDS workload and needs the appropriate RDS licensing architecture.

Administrative access should not be used as a workaround to provide ordinary employees with unlicensed RDS sessions.

Recommended Emergency Procedure

When users report this licensing error, use the following sequence:

User reports RDS licensing error
              ↓
Check whether existing sessions are working
              ↓
Do NOT unnecessarily log off active users
              ↓
Try mstsc /admin
              ↓
Open RD Licensing Diagnoser
              ↓
Check RD Licensing Manager
              ↓
Verify License Server activation
              ↓
Verify appropriate RDS CALs
              ↓
Verify Per User / Per Device mode
              ↓
Verify configured License Server
              ↓
Check licensing service
              ↓
Check GPO
              ↓
Check DNS/network/firewall
              ↓
Correct the underlying problem
              ↓
Test a new normal RDS connection

Key Takeaway

When Windows displays:

“There are no Remote Desktop License Servers available to provide a license.”

do not assume Windows will reserve one normal RDS connection for emergency use.

The practical possibilities include:

Existing user → May remain connected

Disconnected existing session → May be reconnectable

New normal RDS user → May be rejected

Administrator using mstsc /admin → May still be able to administer server

Therefore, administrators should preserve working sessions where practical, use administrative or console access to diagnose the problem, and repair the actual RDS licensing configuration.

Frequently Asked Questions (FAQ)

1. If the RDS license server fails, will at least one user definitely be able to connect?

No. There is no general guarantee that one ordinary RDS user will always be permitted to establish a session during an RDS licensing failure.

2. Can an administrator still connect?

Possibly. Try:

mstsc /admin

This is intended for server administration and troubleshooting, not as a replacement for RDS licensing.

3. Can existing users continue working?

They may. A licensing problem affecting new connection attempts doesn't necessarily immediately terminate all established sessions.

4. Why are five users working while a sixth receives the licensing error?

The five may have existing sessions, or the clients may have different licensing states. Investigate the licensing infrastructure rather than assuming the sixth user has a Windows account problem.

5. Should I log off a working user so another person can connect?

Not as your first troubleshooting step. A logged-off user's session is terminated, and there is no guarantee that a new connection will succeed while the licensing problem remains.

6. Will disconnecting instead of logging off preserve the session?

Normally, disconnecting leaves the session running, while logging off terminates it. However, successful reconnection during a licensing problem should not be assumed.

7. Does the error mean all my RDS CALs have been consumed?

No. The same error can occur because the Session Host cannot locate or communicate with the correct licensing server, the mode is wrong, the server isn't properly activated, or another licensing configuration problem exists.

8. Does it mean the RDS license server is physically offline?

Not necessarily. The licensing server may be online while the Session Host is incorrectly configured or unable to use it.

9. Can I reboot the server to fix it?

A reboot may restart services but won't correct an invalid licensing configuration. It can also disrupt currently working sessions.

10. Where should I check first?

Open:

RD Licensing Diagnoser

Then check Remote Desktop Licensing Manager.

11. How do I open Remote Desktop Licensing Manager?

Run:

licmgr.exe

12. Can RD Session Host and RD Licensing run on the same Windows Server?

Yes, particularly in smaller environments, provided the deployment and licensing are properly configured.

13. Can Group Policy cause this error?

Yes. A local or domain policy can specify the licensing mode and license server, potentially overriding another configuration.

14. What is mstsc /admin?

It requests an administrative Remote Desktop connection for server administration.

15. Can employees use /admin to bypass the RDS license error?

It shouldn't be used as a workaround for ordinary employee RDS access or to bypass RDS licensing requirements.

16. Why did RDS work for months before this error appeared?

One possible reason is expiration of the initial RDS licensing grace period. Other causes include server migration, GPO changes, licensing service failure, network/DNS problems or configuration changes.

17. Can the server itself be perfectly healthy when this error appears?

Yes. CPU, RAM, storage, networking and Windows itself can be operational while the RDS licensing subsystem prevents new normal sessions.

18. Should I delete the RDS GracePeriod registry key?

No. Fix the actual licensing configuration rather than using grace-period manipulation as a licensing workaround.

19. Should I reinstall Windows Server?

Usually not. Diagnose the licensing server, CAL installation, mode, policies and connectivity first.

20. What is the safest approach when some users are still working?

Avoid unnecessarily logging them off. Gain administrative access, diagnose the licensing failure, fix it, and then test a new normal user session.

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