The answer is that the Lambda execution role lacks the s3:GetObject permission for the bucket. This is the most likely cause because when an S3 PUT event triggers the Lambda function, the execution role must authorize the function to read the object it just received; without this permission, the SDK call to retrieve the object fails with AccessDenied. The console test often bypasses this issue because it may use the caller’s own IAM credentials or a different event payload that doesn’t require reading the object. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of how Lambda execution roles differ from invocation permissions—a common trap is confusing the S3 bucket policy (which allows S3 to invoke Lambda) with the role policy (which allows Lambda to read from S3). Remember the memory tip: “Invoke is S3’s job, read is Lambda’s role.”
DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A developer is troubleshooting a Lambda function that processes S3 events. The function runs successfully in the AWS Management Console test but fails when triggered by actual S3 PUT events. The error logs show 'AccessDenied' when attempting to read the object from S3. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Lambda execution role lacks 's3:GetObject' permission for the bucket.
The Lambda function's execution role must have permission to read the S3 object. The error occurs only with actual events because the console test may use a different role or the event payload differs. Option C directly addresses the missing permission. Option A is wrong because S3 events do not require VPC access. Option B is wrong because the bucket policy may not grant access to the Lambda service principal. Option D is wrong because S3 event notifications do not have versioning restrictions.
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 bucket has versioning enabled and the event does not include the version ID.
Why it's wrong here
Versioning does not prevent access; the function can read the latest version without a version ID.
✓
The Lambda execution role lacks 's3:GetObject' permission for the bucket.
Why this is correct
The Lambda role must have permission to read the object from S3.
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 S3 bucket policy does not grant 's3:GetObject' to the Lambda service principal.
Why it's wrong here
The bucket policy should grant access to the Lambda execution role, not the service principal.
✗
The Lambda function is not in the same VPC as the S3 bucket.
Why it's wrong here
S3 is a regional service; VPC configuration is not required for S3 access.
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 DVA-C02 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.
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Lambda execution role lacks 's3:GetObject' permission for the bucket. — The Lambda function's execution role must have permission to read the S3 object. The error occurs only with actual events because the console test may use a different role or the event payload differs. Option C directly addresses the missing permission. Option A is wrong because S3 events do not require VPC access. Option B is wrong because the bucket policy may not grant access to the Lambda service principal. Option D is wrong because S3 event notifications do not have versioning restrictions.
What should I do if I get this DVA-C02 question wrong?
Identify which DVA-C02 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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Question Discussion
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