topic Re: Error -15: Cannot connect to license server, followed troubleshooting guide in Mathcad Installation

Error -15: Cannot connect to license server, followed troubleshooting guide

SD_13039783 — Thu, 19 Feb 2026 16:45:55 GMT

I am using Mathcad Prime Release 11.0 and Datecode11.0.1.0

Error -15: Cannot connect to license server

I installed FlexNet Admin on a virtual machine and configured it as a PTC licensing server. The license file has been configured, and all required ports have been verified as open.

When launching Mathcad Prime and attempting to connect to the license server, the application reports that the license was added successfully. However, when I check the license settings, the server is not actually listed. If I attempt to add the license server manually, I receive the error:

-15: Cannot connect to license server

I followed the PTC troubleshooting guide for Error -15 but was unable to resolve the issue:
https://www.ptc.com/en/support/creo-admin-troubleshooter/error-code/error-15

Any guidance or suggestions to help resolve this issue would be greatly appreciated. Thank you.

Here are the errors that I faced
-15: Cannot connect to license server.

Re: Error -15: Cannot connect to license server, followed troubleshooting guide

VladimirN — Fri, 20 Feb 2026 10:14:18 GMT

Articles:

"Error "(-15) Cannot connect to license server system" while launching FLEXnet enabled applications": https://www.ptc.com/en/support/article/CS44661
"Error "-15, Cannot connect to license server" occurs while launching Creo Parametric however, ptcstatus.bat shows correct license status": https://www.ptc.com/en/support/article/CS369588
"Error "-15, Cannot connect to license server" occurs while launching Creo Parametric on same machine where Flexnet Admin License Server is installed": https://www.ptc.com/en/support/article/CS366725

Re: Error -15: Cannot connect to license server, followed troubleshooting guide

SD_13039783 — Thu, 05 Mar 2026 19:34:29 GMT

Hello,

I tried the guides you provided, but I’m still encountering the same issue. Is there any way to obtain more detailed error messages beyond Error -15? It’s difficult to pinpoint the exact issue with the limited information available.

The wizard indicates that the license was added successfully, but it never actually appears after completion.

Any help would be appreciated. Thank you.