Dear all,
I updated this morning to Zemax 2026 R1.01. Since then I get the following error message when trying to connect to Zemax with Python via API (e.g. by using the PythonStandAlone_01.py file):
“InitializationException: Unable to locate Zemax OpticStudio. Try using a hard-coded path.”
Did anything change here?
Thank you and best regards,
Gregor
Best answer by David.Nguyen
I haven’t installed 2026 R1.01, but I’ve read about similar topics in the past and reinstalling OpticStudio was often enough to solve the issue.
That being said, have you tried using a hard-coded path like the error suggests?
The message is a bit cryptic, but the code is looking for the API library files, usually in \Documents\Zemax\ZOS-API\Libraries (maybe also check that this folder exists for you and that it has files like ZOSAPI_NetHelper.dll) but the way it finds it is through lines like:
# determine location of ZOSAPI_NetHelper.dll & add as reference
aKey = winreg.OpenKey(winreg.ConnectRegistry(None, winreg.HKEY_CURRENT_USER), r"Software\Zemax", 0, winreg.KEY_READ)
zemaxData = winreg.QueryValueEx(aKey, 'ZemaxRoot')
NetHelper = os.path.join(os.sep, zemaxData[0], r'ZOS-API\Libraries\ZOSAPI_NetHelper.dll')where it is looking for a key in the Windows Registry (ZemaxRoot), if that key gets messed up for whatever reason, it can explain the error.
Instead of this line:
NetHelper = os.path.join(os.sep, zemaxData[0], r'ZOS-API\Libraries\ZOSAPI_NetHelper.dll')You could try to supply a hard-coded path:
NetHelper = r'C:\Users\your_username\Documents\Zemax\ZOS-API\Libraries\ZOSAPI_NetHelper.dll'Sorry I don’t have a definite answer, hopefully it helps. The ZOSPy folks might be able to help further
Take care,
Omni
I get the same message for both, extension and standalone. Looks like as if the path to something got lost.
+2
I haven’t installed 2026 R1.01, but I’ve read about similar topics in the past and reinstalling OpticStudio was often enough to solve the issue.
That being said, have you tried using a hard-coded path like the error suggests?
The message is a bit cryptic, but the code is looking for the API library files, usually in \Documents\Zemax\ZOS-API\Libraries (maybe also check that this folder exists for you and that it has files like ZOSAPI_NetHelper.dll) but the way it finds it is through lines like:
# determine location of ZOSAPI_NetHelper.dll & add as reference
aKey = winreg.OpenKey(winreg.ConnectRegistry(None, winreg.HKEY_CURRENT_USER), r"Software\Zemax", 0, winreg.KEY_READ)
zemaxData = winreg.QueryValueEx(aKey, 'ZemaxRoot')
NetHelper = os.path.join(os.sep, zemaxData[0], r'ZOS-API\Libraries\ZOSAPI_NetHelper.dll')where it is looking for a key in the Windows Registry (ZemaxRoot), if that key gets messed up for whatever reason, it can explain the error.
Instead of this line:
NetHelper = os.path.join(os.sep, zemaxData[0], r'ZOS-API\Libraries\ZOSAPI_NetHelper.dll')You could try to supply a hard-coded path:
NetHelper = r'C:\Users\your_username\Documents\Zemax\ZOS-API\Libraries\ZOSAPI_NetHelper.dll'Sorry I don’t have a definite answer, hopefully it helps. The ZOSPy folks might be able to help further
Take care,
Omni
+2By the way, when you reinstall OpticStudio that is also what’s happening. The registry key is overwritten with the potentially correct path. But if you know what you are doing, supplying the path is perhaps the more lightweight approach.
Take care,
David
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