I am facing similar error as mentioned above, by Satyam.

I am importing csv-data to Maxwell-Circuit and creating an .sph file. The .sph is imported to Maxwell2D. This method is working for me in some cases. For example, if the imported circuit has a Piecewise-Linear Voltage element, there is no error and the simulations are working. However, if the circuit has Piecewise-Linear current element, I am getting the error message given below.

    [error] Maxwell2d solver, process solver2d error: Internal Solver Error:  ‘Cannot open file: extnlckt.par!’. Please contact Ansys technical support.
    [error] Simulation completed with execution error on server: Local Machine.