Why do I receive License Manager Error -15?

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Why do I receive "License Manager Error -15"?
On the client system, the error appears as:
ERROR: License checkout failed. Cannot connect to license server. License Manager Error -15.
On the license server, the error appears as:
ERROR: FlexNet Licensing error: -15,10. System Error: 10061 "WinSock: Connection refused"

Accepted Answer

MathWorks Support Team
MathWorks Support Team on 26 Sep 2022
Edited: MathWorks Support Team on 26 Sep 2022
This error can have different meanings depending on which system it occurs.
If you receive this error on a client installation of MATLAB:
  1. Verify communication by pinging the license manager server from the client with the following command: ping <hostname>  where <hostname> is the hostname of the server machine. If this fails you may have a networking error that is preventing the client from communicating with the license manager server. Contact your network administrator to resolve this issue. NOTE: If you know the IP address of the server and are able to ping that, the issue more lies within the DNS configuration of your network. You can replace the hostname in the server line of the network.lic with the IP address as a workaround
  2. Verify that the SERVER line of the network.lic on the client matches that of the license.dat file on the server itself. If the SERVER line differs it may cause the client to contact the wrong server/port.
  3. Check if there is a firewall(s) between the MATLAB client and the license manager server. The license manager communicates on two ports that must be opened through the firewall(s). These ports are specified in the license file hosted on the license manager server. If there is a firewall running, contact your System Administrator to open the necessary ports in the firewall.
  4. If you require a Virtual Private Network (VPN) to connect to the Network License Manager, make sure that you are connected to the VPN.
If you receive this error on the license server:
  1. Verify that the license manager is running on the license server. If the license manager is not running, restart the license manager and try to run MATLAB again. This will often resolve the error. For more information on how to restart the license manager, see instructions: https://www.mathworks.com/matlabcentral/answers/102968-how-do-i-start-or-stop-the-network-license-manager
  2. Verify that the TCP port numbers used by the license manager are not already being used by another application. To determine which port numbers the license manager is using, refer to the end of the SERVER and/or DAEMON lines in the license.dat file.
Note that the license manager uses two ports. The first port is used by lmgrd, and is defined at the end of the SERVER line in the license.dat file. By default, port 27000 is used. The second port is used by MLM, and is (optionally) defined at the end of the DAEMON line in the license.dat file. By default, the port is randomly selected.
SERVER Host_Name HostID 27000
DAEMON MLM <path/to/MLM> port=1711
Note: In this setup both the Host Name and HostID are from the License Server, not the client computer.
If the DAEMON line does not end with "port=<number>", then MLM is using a random open port. In the example above, you will need to check ports 27000 and 1711. Consult your network administrator for help identifying ports in use.
To verify which ports are in use on your system, you can use the "netstat" utility. This utility is called from the DOS prompt for Windows, or through a terminal window on Linux/MacOS. To use the utility, execute the following command:
netstat -aon
For Windows users: to then verify which program is using the port, copy the PID and then put it at the end of the command below:
tasklist | findstr
An example would be:
tasklist | findstr 21592
For more information about these ports, see the article below:
If you are getting this error while connected to a Wide Area Network (WAN), please see the article below:
Ali Naeemah
Ali Naeemah on 26 Sep 2020
the software center of my university told me that the expire date of Matlab 2019a will expire on my 2020 that means now I can not use the university version right now until they update it

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More Answers (20)

pronning on 7 Jul 2017
To me, the error occured when I was off-site, and the VPN to the University server was disconnected...
Gjermund Holøyen
Gjermund Holøyen on 25 Feb 2022
Thank you! It's funny how the replies always are so much better at providing the solution.

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Wenxuan Liang
Wenxuan Liang on 16 Feb 2021
This happened to me seemingly because that nmy university has updated the license, so my old MATLAB 2017b on one long-unused computer could not start.
The solution here is simple. Assuming you have an updated license (through the University probably), simply go to the installation directory ("C:\Program Files\MATLAB\R2017b" for me), and locate "<MATLAB DIR>\bin\win64\activate_matlab.exe", and then run it to re-enter the license information.
No need to re-install MATLAB.
Evangeline Eigbobo
Evangeline Eigbobo on 8 Oct 2022
Just tried it.. It works!. Thank you so much!!.This was very helpful to me.

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Mariusz Pawlak
Mariusz Pawlak on 7 Oct 2021
I found that on license server manager computer must be enabled mlm.exe connection by windows firewall. That was my case, that is why I couldnt connect to license.
Regards :)
Mariusz Pawlak
Mariusz Pawlak on 25 Nov 2021
Try to switch off Windows firewall or antivirus firewall if You have ( temporary od course :) if this fix the problem than the problem is with closed ports

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Bradley Evans
Bradley Evans on 19 Sep 2022
No wonder many students are choosing Python over MATLAB. So, we download, install it, but still can't use it. Chalk up another one for the gurus at MathWorks!

Asma on 8 Jul 2017
I got this problem but it was like intermittence connection. Sometimes there is no error, sometimes not ok and appears this error. Ping the hostname is successful. I don't know how to solve it.

Leonid Tulin
Leonid Tulin on 11 Oct 2017
I have that error after force-quit . Server works fine . How can i fix it ??
Tech Support
Tech Support on 6 Jun 2018
Hi Laurent,
If you are still experiencing this issue, please contact MathWorks support:

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Anuradha Das
Anuradha Das on 16 Feb 2018
i could not open the matlab r2017a due to licence failure..kindly assist me
  1 Comment
Riley Holzman
Riley Holzman on 24 Apr 2018
You have to wait for your teacher. she will tell you.

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blue ece
blue ece on 8 Mar 2018
how i can install matlab
Kyle Perry
Kyle Perry on 20 Jun 2018
Hi Will,
It should not have been adjusting the port number on its own, if this happens again, please contact us so we can take a look at the issue.
Regards, Kyle Perry

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h612 on 21 May 2018
I am using Matlab2017a from my university. I just figured out that using any network besides that of my universities', I had the license server issue. Hope that helps sm1.

Alfonso Valdes
Alfonso Valdes on 25 Oct 2018
Hi, I just migrated to Mac OS Mojave and got the license message the first time I tried to use Matlab under Mojave. The license path in the message is /Library/Application Support/MathWorks/MATLAB/R2017b_licenses:/Applications/MATLAB_R2017b.app/licenses/license.dat:/Applications/MATLAB_R2017b.app/licenses/network.lic
But if I ls from /Library/Application Support/MathWorks/MATLAB, I just see the directory R2017b and there is no license. Anyone else seeing this? Have you migrated to Mojave?
Kyle Perry
Kyle Perry on 14 Feb 2019
Hello Everyone,
If you are still receiving the error after trying all the steps listed above, then please contact our support team so we can assist.

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Dhritiraj Sengupta
Dhritiraj Sengupta on 13 Jul 2019
Hello, I am having the following error. How can I fix it?
WeChat Screenshot_20190713142256.png

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Toon Verwaest
Toon Verwaest on 8 Apr 2020
License checkout failed. License Manager Error -15
MATLAB is unable to connect to the license server. Check that the license manager has been started, and that the MATLAB client machine can communicate with the license server.
LAMPROS RAMMOS on 21 Jan 2021
και πως ακριβως κατεβαζουμε το vpn του ΕΜΠ ?

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Jacques Richou
Jacques Richou on 13 Jan 2021
Hello there,
My MatLab was working just fine last time I used it, I was not in school, but at home to try it 1st time
Next, when it did not work, I was at my girlfriends appartment when it showed me the License Error
No VPN used anywhere, and other students did not have the same issue.
I reinstalled Matlab, and it did not change anything, f someone has an idea about how to solve this, I'll take =)
Have a nice one =)

Devki Talwar
Devki Talwar on 9 May 2022
MatLab License Issue

Dale Logan
Dale Logan on 16 May 2022
ERROR: License checkout failed. Cannot connect to license server. License Manager Error -15.

Navneet Upadhyay
Navneet Upadhyay on 18 Jul 2022
MatLab License Issue

Zaman Ali
Zaman Ali on 20 Jul 2022

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Enayat Mahajerin
Enayat Mahajerin on 23 Jul 2022
Refused Connection

Zhongshan Li
Zhongshan Li on 14 Aug 2022
I would like to continue to have access when my VPN connection to my university, Georgia State University, is disconnected.
  1 Comment
Walter Roberson
Walter Roberson on 23 Jan 2023 at 20:34
This is possible if the university agrees to configure to "borrow" licenses; see https://www.mathworks.com/help/install/license/borrow-licenses.html

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Amrarul Islam
Amrarul Islam on 5 Jan 2023 at 23:55
why I can not connect with VPN matlab ?


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