Hi Eric,

I’m assuming you are generating the tepmlate code from the latest OpticStudio version: Programming > Python > Standalone Application / Interactive Extension.

Can you tell us your version of Pythonnet as well? There have been issues with Pythonnet 3.0.0 and Zemax recommend using Pythonnet 2.5.2 for the moment:

• ZOS-API supporting Python 3.10 and python.Net 3.0?

Take care,

David

Hi David, 

Thank you for the advice. Yes, I am generating the template from that method. 

I have uninstall Pythonnet 3.0.0 and installed 2.5.2. However, the error continue to occur. 

Is there any other method/way I could try ? 

Hi @Eric.Aw,

I’m wondering if you are missing a required package for Python. In order for clr to work properly, you need to install the Pythonnet library. It could be corrupted as well, so try uninstalling/reinstalling it if you’ve already added it to your Python installation.

There are also some good suggestions here in this Community article: ZOSAPI_NetHelper cannot be added | Zemax Community.

Best,
Ethan 

Hi @Ethan , @Sandrine Auriol 

Thank you very much for the advice. 
At the end , I uninstall everything (python and spyder) and install everything again. Then follow some of the guide above and it works. 

Thank you 

Hi @Eric.Aw,

I’m glad to hear you got it working! Thanks for updating the Community with your findings.

Best,
Ethan