Errors or warnings triggered by a problem with the GAMS license file (license.txt) are reported both in the log file and in the lst file. Below are some typical error, warning messages and instructions how to overcome them.
Without a license file GAMS will work as a free demonstration mode with these limitations:
The GAMS log will indicate that your system runs in demo mode:
GAMS Rev 149 Copyright (C) 1987-2007 GAMS Development. All rights reserved Licensee: GAMS Development Corporation, Washington, DC G871201/0000CA-ANY Free Demo, 202-342-0180, email@example.com, www.gams.com DC0000 --- Starting compilation
and GAMS will terminate with a licensing error if you hit one of the limits above:
*** Status: Terminated due to a licensing error *** Inspect listing file for more information
gamslice.txt), please copy it as to your GAMS system directory (e.g.
c:\Program Files\GAMS22.8). Do not try to rename it or to modify the contents of the license file.
Running GAMS with an invalid license will produce a log file like the one below:
*** License File validation failed *** System downgraded to demonstration mode ...
*** License file too old for this version of GAMS. *** Maintenance expired 2840 days ago. *** More than 60 days since expiration, sorry... *** System downgraded to demonstration mode *** Run an older GAMS system or renew the license
A GAMS license is perpetual, but can only be used in connection with a GAMS system issued within the free maintenance period. By default this is one year after the purchase of the system. If you run an old license file with a GAMS system, that has been issued after that period, you will get the error message above and the system will downgrade to the demonstration mode. You can now either
*** No license found *** To update your license, please contact your distributor. *** Too many equations for demo mode
You are using a valid license file for GAMS/BASE, but one of the solvers you are using for the optimization are not included in the license and the size of the model exceed the limits of the demo license. Check whether the default solvers for a particular problem class are included in the license. Please note that some of the solvers call other solvers as a sub-solver, e.g.:
The complete error message is:
*** License file too old for this version of GAMS. *** Maintenance expired xxx days ago. *** More than 60 days since expiration, sorry... *** System downgraded to demonstration mode *** Run an older GAMS system or renew the license
The error message is self-explaining. The license file (
gamslice.txt) you are currently using is too old for this version of GAMS. Please make sure that you are always using the latest version of license file, that has been e-mailed to you or use an older distribution.
This warning (without further error messages) indicates that the evaluation license file you are using is still valid, but will downgrade to the limits of the free demonstration version very soon.
The complete message is:
*** License file too old for this version of GAMS. *** Maintenance expired xx days ago. ..
but the GAMS runs continues. In general, you can ignore this warning and continue using that distribution with your current license file. However, any forthcoming GAMS distribution will most likely not work, but downgrade to the limits of the demonstration mode.