-2147024809, System.ArgumentException
What causes it and how to fix it:
- fields/getbyinternalnameortitle returns 400, not 404, for a missing fieldIt throws ArgumentException (HTTP 400), not 404; an existence-check that hard-fails on non-404 breaks the "field missing → create" path, and one that creates on any non-200 duplicates the column when throttledCause and fix →