Hi Jason,
Did you turn on the logs to check what causing the error? It's null pointer exception as I am seeing it from here.
I will suggest you to create the object structure by duplicating the MXTOOLITEM out-of-box OS and keep only the objects you are interested in (i.e TOOLITEM here). Don't change anything else and then use that OS for uploading the tool item data.
Let me know how it goes.
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Subhransu Sekhar Sahoo
Tata Consultancy Services
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