The answer is to enable S3 versioning on the bucket and configure the pipeline to reference the specific version ID. This resolves the CodePipeline S3 object exist error race condition because when an external system overwrites a source artifact by deleting and re-uploading it with the same key, CodePipeline’s reference to the original object becomes stale—the pipeline tries to download an object that no longer exists at that key. Without versioning, the object is permanently replaced, but with versioning enabled, the old version remains accessible, and by pinning the pipeline to a specific version ID, you eliminate the race condition entirely. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how CodePipeline resolves S3 objects at trigger time versus execution time, and the common trap is assuming the pipeline dynamically follows the latest object. A helpful memory tip: versioning gives your pipeline a “snapshot in time,” so the object can’t be swapped out mid-execution.
DOP-C02 SDLC Automation Practice Question
This DOP-C02 practice question tests your understanding of sdlc automation. 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 company uses AWS CodePipeline with a source stage from Amazon S3 and a deploy stage to AWS Elastic Beanstalk. The pipeline has been working for months, but recently the deploy stage started failing with the error 'The S3 object does not exist.' The source artifact is uploaded to the S3 bucket by an external system. Which TWO actions should be taken to resolve this issue? (Choose TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Ensure the external system does not overwrite the object after the pipeline execution starts.
Option A is correct because the deploy stage fails with 'The S3 object does not exist' when the external system overwrites the source artifact after the pipeline execution starts. CodePipeline references the object by its key at the time the pipeline is triggered; if the object is replaced (i.e., deleted and re-uploaded with the same key), the pipeline may attempt to download a version that no longer exists, especially if the S3 bucket is not versioned. Ensuring the external system does not overwrite the object during execution prevents this race condition.
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.
✓
Ensure the external system does not overwrite the object after the pipeline execution starts.
Why this is correct
Preventing overwrites ensures the object remains available.
Related concept
Read the scenario before looking for a memorised answer.
✗
Change the source stage to use AWS CodeCommit instead of S3.
Why it's wrong here
Changing source type is unnecessary and may not address the root cause.
✓
Enable versioning on the S3 bucket and configure the pipeline to use the specific version ID.
Why this is correct
Versioning allows the pipeline to reference a fixed version of the artifact.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use server-side encryption with AWS KMS (SSE-KMS) on the S3 bucket.
Why it's wrong here
Encryption does not affect object existence.
✗
Increase the timeout for the deploy stage in the pipeline.
Why it's wrong here
Timeout does not address the object not existing.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume the error is due to a permission or encryption issue (like SSE-KMS) rather than recognizing it as a classic race condition caused by object overwriting in a non-versioned bucket.
Detailed technical explanation
How to think about this question
Under the hood, CodePipeline uses the S3 GetObject API with the exact key and (if versioning is disabled) the latest version. When an object is overwritten without versioning, the old version is permanently replaced, and any in-flight pipeline execution referencing the original ETag or last-modified timestamp may fail. Enabling S3 versioning and configuring the pipeline to use a specific version ID (Option C) decouples the pipeline from overwrite events, as each upload creates a new version and the pipeline can be pinned to a stable version ID.
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.
TExam Day Tips
→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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
SDLC Automation — This question tests SDLC Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Ensure the external system does not overwrite the object after the pipeline execution starts. — Option A is correct because the deploy stage fails with 'The S3 object does not exist' when the external system overwrites the source artifact after the pipeline execution starts. CodePipeline references the object by its key at the time the pipeline is triggered; if the object is replaced (i.e., deleted and re-uploaded with the same key), the pipeline may attempt to download a version that no longer exists, especially if the S3 bucket is not versioned. Ensuring the external system does not overwrite the object during execution prevents this race condition.
What should I do if I get this DOP-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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