Hi @lq_c ,
Object reference not set to an instance of an object means a variable you’re referencing is null/haven’t been initialized. I would recommend doing a review of your variables and arguments to ensure the data you need is available at the scope you need it.
A few things you can review:
- Variables have a value before referencing them
- Data structures like lists and dictionaries may need to be initialized on its first use
- Verify your arguments have the appropriate direction in, out, in/out
- Verify the scope of your variable is not limited to a sub-sequence that your code can’t reach.
hope this helps! 