DEA-C01 Data Ingestion and Transformation Practice Question
Exhibit
Refer to the exhibit. 2019-11-15T10:00:00Z ERROR: Task failed: 'NoneType' object has no attribute 'read'
Refer to the exhibit. A data engineer is running an AWS Glue job that reads data from an S3 source. The job fails with the error shown. What is the MOST likely cause?
⚠ Common exam trap
Watch out — candidates often assume permission errors (Option A) are the default cause of any S3-related failure, but the specific error message (NullPointerException) points to data corruption or empty files, not access control issues.
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
✓
One of the source files is empty or corrupted.
The error message indicates that the Glue job encountered a 'NullPointerException' or similar parsing failure when reading from S3. This typically occurs when a source file is empty or corrupted, causing the Spark DataFrame reader to fail during schema inference or data parsing. AWS Glue jobs rely on Spark's ability to read files; an empty or malformed file triggers a runtime error because Spark cannot extract any records or infer a valid schema from 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 IAM role does not have s3:GetObject permission.
Why it's wrong here
Would cause access denied.
- ✓
One of the source files is empty or corrupted.
Why this is correct
Empty file can return None when read, causing 'NoneType' has no attribute 'read'.
- ✗
The file is in JSON format but the schema expects Parquet.
Why it's wrong here
Would cause a parsing error.
- ✗
The Glue job has insufficient memory allocated.
Why it's wrong here
Would cause out-of-memory error.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-C01 practice question is part of Courseiva's free Amazon Web Services 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 DEA-C01 exam.