Databricks-DE-Pro Debugging and Deploying Practice Question
A data engineer is deploying a Databricks job that uses a Python wheel task. The job fails with the error: 'ModuleNotFoundError: No module named 'my_library''. The wheel file is stored in DBFS at 'dbfs:/FileStore/wheels/my_library-0.1.0-py3-none-any.whl'. The job cluster is configured with a cluster policy that restricts library installation from DBFS. What is the most likely cause of the failure?
⚠ Common exam trap
The trap here is focusing on the wheel's compatibility or path syntax instead of the cluster policy restriction that blocks installation from DBFS.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The cluster policy prevents installing libraries from DBFS, so the wheel was not installed.
The error indicates that the Python module 'my_library' is not available in the job cluster's environment. Since the wheel is stored in DBFS and the cluster policy restricts library installation from DBFS, the wheel was not installed. The engineer must either modify the cluster policy to allow DBFS libraries or relocate the wheel to a permitted source, such as a Unity Catalog volume or cloud storage, and then install it.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The job cluster does not have the 'pip' package manager installed.
Why it's wrong here
Databricks clusters come with pip pre-installed in the Python environment. It is highly unlikely that pip is missing. Even if pip were missing, the error would be different, such as a command not found. The ModuleNotFoundError indicates that the library was not installed, not that the installation tool is absent.
- ✗
The wheel file path is incorrect; it should be 'dbfs:/FileStore/wheels/my_library-0.1.0-py3-none-any.whl' without the 'dbfs:/' prefix.
Why it's wrong here
The 'dbfs:/' prefix is correct for DBFS paths in Databricks. Omitting it would be incorrect. The error is not about path resolution; if the path were wrong, the error would indicate that the file could not be found, not that the module is missing. The path is likely valid, but the installation is blocked by policy.
- ✓
The cluster policy prevents installing libraries from DBFS, so the wheel was not installed.
Why this is correct
Cluster policies can restrict library sources. If the policy disallows DBFS libraries, the wheel will not be installed, leading to the ModuleNotFoundError. This is the most likely cause because the error explicitly states the module is missing, and the policy restriction directly prevents installation. The engineer should either adjust the policy to allow DBFS or move the wheel to a supported location like Unity Catalog volumes or cloud storage.
- ✗
The wheel file is not compatible with the cluster's Python version.
Why it's wrong here
A Python version mismatch would typically result in a different error, such as 'ImportError: dynamic module does not define module export function' or a syntax error. The error 'No module named' indicates that the library is not installed at all, not that it's incompatible. While compatibility is important, it is not the primary cause here given the cluster policy restriction.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Databricks exam blueprint
This Databricks-DE-Pro practice question is part of Courseiva's free Databricks certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the Databricks-DE-Pro exam.