Thanks for the reply.

I tried assigning Application.persistentDataPath, which should work on Hololens, but unfortunately I'm still getting the same exception in the first post. The Hololens does have access to both streamingAssetsPath and persistentDataPath, so I don't think that's the issue here.

Could the OPCUA client be trying to access some other directory that's causing the exception?

Hi, I noticed that I'm getting another exception when calling OPCUA_Interface.Connect() from Hololens:

"UnauthorizedAccessException: Failed getting the path of a special folder: Access Denied."

This comes from line 264 in OPCUA_Interface.cs, where it's trying to access the Common Application Data folder. It seems that the app does not have permission to access this folder in the Hololens. Is having access to this folder vital for OPCUA4Unity to work? I'm not sure if this is related to the exception I'm getting in the first post, but just thought I'd bring this up.