topic Why this notebook is returning an error only when called by another notebook? in Data Engineering

Why this notebook is returning an error only when called by another notebook?

Saf4Databricks — Wed, 18 Mar 2026 20:07:35 GMT

When I uncomment the last two lines of Called_Notebook.py and run it manually by itself, it correctly returns the output as:

Status: SUCCESS
Circle area: 50.26544

But when I comment out the last two lines of Called_Notebook.py and run it from the Caller_Notebook.py, it returns the output as "None" from the Exception block of the area_of_circle(r) function defined in the Called_Notebook.py. Question: Why the function is failing when called from Caller_Notebook.py ?

Called_Notebook.py:

dbutils.widgets.text("radius", "4") r = float(dbutils.widgets.get("radius")) status="" try: def area_of_circle(r): return 3.14159 * r * r circle_area = area_of_circle(r) status = "SUCCESS" except Exception as e: circle_area = None status = "ERROR" error_message = str(e) # print(f"Status: {status}") # print(f"Circle area: {circle_area}")

Caller Notebook:

try: output = dbutils.notebook.run("./Called_Notebook.py",60,{"radius":"4"}) print(output) except Exception as e: print("Child notebook failed:", e)

Re: Why this notebook is returning an error only when called by another notebook?

pradeep_singh — Thu, 19 Mar 2026 02:22:50 GMT

dbutils.notebook.run() returns only what the called notebook passes to dbutils.notebook.exit().

If your called notebook in the end add this

dbutils.notebook.exit(f"{Value to return}")

Re: Why this notebook is returning an error only when called by another notebook?

Saf4Databricks — Thu, 19 Mar 2026 18:20:03 GMT

Hi @pradeep_singh, your suggestion worked. Thank you for sharing your knowledge. Worth noticing that not including dbutils.notebook.exit(f"{Value to return}") raised the error in the exception block of the function inside the Called_Notebook - and that had confused me. Now, I know.