Python intregration error


I am unable to run FDTD solver using Python script.
I used attached script to run the FDTD solver, it POP-up the solver window, but with an error. I checked the path of the API, it seems to be fine. Can someone help?
PS : Don’t suggest me to upgrade software, as I am already using updated version of FDTD (FDTD Solutions 2018b R1 (v8.20.1634) for Windows (64 bit)). I upgraded this version last week itself. My OS is Window 10. (5.1 KB)


The error indicates you do not have the Automation API license for the Python Integration feature.

Please refer to this KB guide for more information on Python Integration:

You can obtain a trial license for the Automation API from our trials downloads page:
-using the Custom Evalution button.



There is no information on given link that I need to install the new license for Python integration with Lumerical. According to link, the API is already available in a specific folder (Windows: C:\Program Files\Lumerical$(PRODUCT)\api\python) and we need to just point that folder while importing this. The commands for importing this is following.

import imp
lumapi = imp.load_source("lumapi", "/opt/lumerical/interconnect/api/python/")

If I understood properly from this link, it does not require any additional license.

Anyway, I visit to the link,
and try to get the details. It seems like it will give me a trial license. So, I got a trial license from here. Now, I don’t understand what to do with this.
My system already has one license key, so if I try to enter this new key, it is basically asking me to deactivated previous license. This means this trial license will expire after one month. So, after that should I again need to go back to the previous license?

I mean this is really strange if I need an additional license just to integrate python with Lumerical. It must be simple as we already have integration of Matlab with Lumerical.


Hi @visvas,

As shown from the screenshot I provided on the Python Integration page, the first Requirement is the Automation API license.

Yes, the Python API module is supplied with all our design tools. But using this and integrating with our tools will require a separate license.

For MATLAB API use and integration, there is no need for any separate license.

As for the trial license you obtained from our website for Windows. This is a NODE locked license, which is the default license type for this OS. It cannot be activated using the FlexNet license manager activation utility.

From the screenshot, you Purchased a Floating License for our design tools. Unfortunately, the NODE locked license cannot be mixed with a Floating license.

Please send a request for a Floating trial license for your existing Purchased Floating License to

Hope this clarifies everything.


This is really said to know that Python integration (an open source software) required seprate license while Matlab doesn’t require it. It doesn’t make any sense for me. Anyhow one can not use Python integration without having your licenses of solver. So, it’s like visulizing something in Python is paid but in Matlab it’s free.
This request must be raise to management level to make it free.

SIncelry, nothing to cheers in this case. :frowning_face:


Please feel free to raise your request in our Ideas Exchange.

This is a portal where users can provide feedback and ideas on how to improve our tools. It will also allow other users to vote on your requests.