The correct answer is that the job is reading a CSV file that was incorrectly placed in the directory with a .parquet extension. This is because the AWS Glue job is configured to expect only Parquet files, and when it attempts to parse a CSV file as Parquet, the schema mismatch triggers the "invalid Parquet file" error in CloudWatch Logs. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how Glue’s schema inference and file format handling work, especially when mixed file types exist in the same S3 prefix. A common trap is to assume the error is about missing files or permissions, but the error message explicitly points to a format issue. Remember the memory tip: "If it’s not Parquet, it’s a format reject" — always check the file extension and content type when debugging Glue job failures.
DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
2024-01-15T10:30:00Z ERROR 123456789012 i-0abcd1234efgh5678 {"errorCode": "InvalidS3ObjectException", "errorMessage": "The specified S3 object is not a valid Parquet file."}
Refer to the exhibit. A data engineer sees this error in CloudWatch Logs from an AWS Glue ETL job. The job reads from an S3 location that contains both .parquet and .csv files. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
2024-01-15T10:30:00Z ERROR 123456789012 i-0abcd1234efgh5678 {"errorCode": "InvalidS3ObjectException", "errorMessage": "The specified S3 object is not a valid Parquet file."}
A
The S3 object was deleted during the job execution.
Why wrong: Deletion would cause a different error.
B
The IAM role does not have permission to read the S3 object.
Why wrong: Permission errors would be AccessDenied.
C
The job is reading a CSV file that was incorrectly placed in the directory with .parquet extension.
The file might have .parquet extension but be CSV, or the job is reading all files regardless of extension.
D
The Glue job does not have enough memory to parse the Parquet file.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The job is reading a CSV file that was incorrectly placed in the directory with .parquet extension.
Option B is correct because the error indicates that the object is not a valid Parquet file. Since the job expects Parquet, it likely encountered a CSV file. Option A is wrong because the error specifically says invalid Parquet, not missing file. Option C is wrong because insufficient memory would cause OOM errors. Option D is wrong because the error is about the object's format, not permissions.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 S3 object was deleted during the job execution.
Why it's wrong here
Deletion would cause a different error.
✗
The IAM role does not have permission to read the S3 object.
Why it's wrong here
Permission errors would be AccessDenied.
✓
The job is reading a CSV file that was incorrectly placed in the directory with .parquet extension.
Why this is correct
The file might have .parquet extension but be CSV, or the job is reading all files regardless of extension.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Glue job does not have enough memory to parse the Parquet file.
Why it's wrong here
Memory issues cause different errors.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Data Operations and Support — This question tests Data Operations and Support — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The job is reading a CSV file that was incorrectly placed in the directory with .parquet extension. — Option B is correct because the error indicates that the object is not a valid Parquet file. Since the job expects Parquet, it likely encountered a CSV file. Option A is wrong because the error specifically says invalid Parquet, not missing file. Option C is wrong because insufficient memory would cause OOM errors. Option D is wrong because the error is about the object's format, not permissions.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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