Could not initialize DLL

AIMMS Knowledge Base Article - KB00001

Could not initialize DLL


You must have an AIMMS license that allows you the use of a solver, and a license for the solver in case you have a 'link only' license, before being able to use a solver in AIMMS. 


When you try to add a solver in the solver configuration dialog, the following error message appears:

        Could not initialize DLL libcpx126.dll

Where libcpx126.dll can also be any other solver DLL that is supported by AIMMS.


There are several possible causes for this problem:

  • You have a license to use AIMMS with CPLEX, but the CPLEX solver files (.cpx) are out of maintenance.
  • Your AIMMS license does not allow the use of this solver.
  • You do have an AIMMS license with solver link, but the solver license is not setup correctly.


For the several causes there are different resolutions:

To update your CPLEX solver files, you can contact us at Please, mention your license number(s) for which you need the new files. Note that your license must be in maintenance to update your solver files.

When you want to use a solver that is not yet supported by your AIMMS license, you need to upgrade your AIMMS license with a solver link (in case you already have a license to the solver), or with a solver.

If you have purchased an AIMMS license with 'link-only' you are able to use your own solver license in combination with AIMMS. Note, that BARON, CBC, CONOPT, IPOPT and XA cannot be used with link-only. To link the solver, please follow the steps described in this knowledge base article: how to link a solver to AIMMS.

More information

For more information, please contact us at