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"


MathWorks Support Team
编辑:MathWorks Support Team 2022-9-26
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:
  6 个评论
Ali Naeemah
Ali Naeemah 2020-9-26
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


更多回答(23 个)

pronning 2017-7-7
To me, the error occured when I was off-site, and the VPN to the University server was disconnected...
  5 个评论


Wenxuan Liang
Wenxuan Liang 2021-2-16
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.

Bradley Evans
Bradley Evans 2022-9-19
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!

Mariusz Pawlak
Mariusz Pawlak 2021-10-7
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 :)
  2 个评论
Mariusz Pawlak
Mariusz Pawlak 2021-11-25
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


Asma 2017-7-8
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 2017-10-11
I have that error after force-quit . Server works fine . How can i fix it ??

Anuradha Das
Anuradha Das 2018-2-16
i could not open the matlab r2017a due to licence failure..kindly assist me

blue ece
blue ece 2018-3-8
how i can install matlab
  4 个评论
Kyle Perry
Kyle Perry 2018-6-20
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


h612 2018-5-21
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 2018-10-25
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?
  2 个评论
Kyle Perry
Kyle Perry 2019-2-14
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.


Dhritiraj Sengupta
Dhritiraj Sengupta 2019-7-13
Hello, I am having the following error. How can I fix it?
WeChat Screenshot_20190713142256.png
  8 个评论
Walter Roberson
Walter Roberson 2023-4-6
Organizational licensing of pretty much anything is messy and can require IT experts.
Mathworks sells "floating licenses" that by default allow anyone who can access the license server to use the full set of toolboxes that the organization has purchased. The license manager just keeps track of the total number of licenses in active use, to ensure that the peak number is within the contracted limit. This does not take much configuration work.
But organizations often prefer (partly for cost reasons) to instead license on a more fine-grain, such as only permitting certain departments to access MATLAB at all, or only permitting certain departments to use particular toolboxes. In any organization that uses "financial cost centres" (very very common), it is likely that each cost centre is under pressure to keep costs down, so costs centres don't want to make the licenses that came out of their budget to be available to other cost centres that are not contributing to the price. So you tend to get detailed role and project tracking, and LDAP (or similar) servers to manage that information, and the MATLAB license has to be hooked into that structure. Mathworks does not require that level of control, but internal political reasons do require that level of control.
For example if you were internally moved from a core mathematics part of a project to UI for the same project, then someone might have decided that the UI people should not have access to the Unit Test framework that the core mathematics project paid for, so some control information has to be updated to reflect that. If your former core-mathematics co-workers ask you to take a look at something, you might now have become unable to do so -- unless, that is, the managers of UI and core-mathematics come to a formal agreement to share your time (even if only for a couple of hours.)
Mathworks is not imposing these level of complications; these kind of complications arise by themselves in most organizations that have different groups competing for scarce resources.
About the only thing that Mathworks could do to eliminate that kind of issue would be to make Mathworks free, and therefore no longer a scarce resource. And even then you are likely to see internal fighting over who pays the IT administrators to install MATLAB and keep it updated.


Toon Verwaest
Toon Verwaest 2020-4-8
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.
  10 个评论
και πως ακριβως κατεβαζουμε το vpn του ΕΜΠ ?


Jacques Richou
Jacques Richou 2021-1-13
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 2022-5-9
MatLab License Issue

Dale Logan
Dale Logan 2022-5-16
ERROR: License checkout failed. Cannot connect to license server. License Manager Error -15.

Navneet Upadhyay
Navneet Upadhyay 2022-7-18
MatLab License Issue

Zaman Ali
Zaman Ali 2022-7-20
  5 个评论


Enayat Mahajerin
Enayat Mahajerin 2022-7-23
Refused Connection

Zhongshan Li
Zhongshan Li 2022-8-14
I would like to continue to have access when my VPN connection to my university, Georgia State University, is disconnected.

Amrarul Islam
Amrarul Islam 2023-1-5
why I can not connect with VPN matlab ?

Daniel Zachary
Daniel Zachary 2023-2-5
I am attempting to log into matlab. I recently changed my password on my university account and things are not lining up. thx for your help
  1 个评论
Walter Roberson
Walter Roberson 2023-2-5
Sorry, the volunteers who answer questions here do not have access to the license database. You will need to contact Mathworks Support


Kar 2023-2-8
编辑:Walter Roberson 2023-2-8
Why is my MATLAB showing license checkout fail when trying to lucnch it?
License manager error 15
cannot connect to license server ntework
  2 个评论
Walter Roberson
Walter Roberson 2023-2-8
I already responded to you with specific steps you can take to help debug the problem. Just saying again that you are having problems contacting the license server does not give us any more information to help us figure out exactly why the problem is happening in your situation.


jones Sefatsa
jones Sefatsa 2023-3-16
ERROR: License checkout failed. Cannot connect to license server. License Manager Error -15.


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