- A
The app.yaml file incorrectly specifies 'runtime: python27' but the code uses Python 3, and python27 does not automatically install dependencies from requirements.txt.
Python 2.7 runtime requires manually specifying libraries in app.yaml.
- B
The custom entrypoint in app.yaml bypasses the automatic installation of dependencies.
Why wrong: Entrypoint only specifies command, not dependency installation.
- C
The app.yaml file specifies 'runtime: python39' which is not supported by App Engine standard.
Why wrong: python39 is a supported runtime.
- D
The requirements.txt file is missing from the deployment directory.
Why wrong: The team says it was configured correctly and not changed.
Question 609 of 999
Fixing 'ImportError: No module named requests' in App Engine
This PCD practice question tests your understanding of building and testing applications. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: app Engine standard runtime. 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.
You are a Cloud Developer working for an e-commerce company. The company uses Cloud Build to build and deploy a Python application to App Engine standard environment. The application uses Cloud SQL for its database. The team recently updated the application code and added a new dependency. The build succeeds, but the deployment fails with 'Error Response: [9] Application startup error!' You check the logs and see 'ImportError: No module named requests'. The team uses a requirements.txt file. However, the requirements.txt file has been configured correctly in the past. The team also uses a custom runtime config in app.yaml with a 'entrypoint' field. They did not change any configuration files. What is the most likely cause of this error?
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.
Quick Answer
The answer is that the app.yaml file incorrectly specifies `runtime: python27` while the code uses Python 3, causing the deployment to fail with an `ImportError: No module named requests`. This happens because the App Engine standard Python 2.7 runtime does not automatically install dependencies from a `requirements.txt` file—it relies on the `libraries` section in app.yaml instead. In contrast, the Python 3 runtime automatically reads `requirements.txt` and installs all listed packages during deployment. On the Google Professional Cloud Developer exam, this scenario tests your understanding of how App Engine runtimes handle dependency management, a common trap where candidates assume all Python runtimes behave identically. The key distinction is that Python 2.7 requires explicit library declarations, while Python 3 expects a `requirements.txt` file. A quick memory tip: Python 3 is "self-serve" from requirements.txt, while Python 2.7 needs a "menu" in app.yaml.
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 app.yaml file incorrectly specifies 'runtime: python27' but the code uses Python 3, and python27 does not automatically install dependencies from requirements.txt.
Option A is correct because the error 'ImportError: No module named requests' indicates that the dependency was not installed. In App Engine standard, when using 'runtime: python27', dependencies listed in requirements.txt are not automatically installed; you must use a third-party library or vendor them manually. Since the team uses a custom entrypoint in app.yaml, this does not override the runtime's default behavior for Python 2.7, which does not support automatic dependency installation from requirements.txt.
Key principle: App Engine standard runtime
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 app.yaml file incorrectly specifies 'runtime: python27' but the code uses Python 3, and python27 does not automatically install dependencies from requirements.txt.
Why this is correct
Python 2.7 runtime requires manually specifying libraries in app.yaml.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
App Engine standard runtime
- ✗
The custom entrypoint in app.yaml bypasses the automatic installation of dependencies.
Why it's wrong here
Entrypoint only specifies command, not dependency installation.
- ✗
The app.yaml file specifies 'runtime: python39' which is not supported by App Engine standard.
Why it's wrong here
python39 is a supported runtime.
- ✗
The requirements.txt file is missing from the deployment directory.
Why it's wrong here
The team says it was configured correctly and not changed.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common misconception is that the custom entrypoint in app.yaml controls dependency installation, when in fact it is the runtime setting that determines whether requirements.txt is processed automatically.
Trap categories for this question
Command / output trap
Entrypoint only specifies command, not dependency installation.
Detailed technical explanation
How to think about this question
In App Engine standard, the Python 2.7 runtime (python27) does not automatically install dependencies from requirements.txt; instead, you must use the 'libraries' section in app.yaml for built-in libraries or vendor third-party packages using the '--target' flag with pip. The Python 3 runtime (e.g., python39) automatically installs dependencies from requirements.txt during deployment. The custom entrypoint field in app.yaml only specifies the command to start the application (e.g., 'gunicorn -b :$PORT main:app') and does not affect dependency installation behavior.
KKey Concepts to Remember
- App Engine standard runtime
- requirements.txt
- app.yaml entrypoint
- ImportError
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
App Engine standard runtime
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. App Engine standard runtime Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Review app Engine standard runtime, then practise related PCD questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this PCD question test?
Building and testing applications — This question tests Building and testing applications — App Engine standard runtime.
What is the correct answer to this question?
The correct answer is: The app.yaml file incorrectly specifies 'runtime: python27' but the code uses Python 3, and python27 does not automatically install dependencies from requirements.txt. — Option A is correct because the error 'ImportError: No module named requests' indicates that the dependency was not installed. In App Engine standard, when using 'runtime: python27', dependencies listed in requirements.txt are not automatically installed; you must use a third-party library or vendor them manually. Since the team uses a custom entrypoint in app.yaml, this does not override the runtime's default behavior for Python 2.7, which does not support automatic dependency installation from requirements.txt.
What should I do if I get this PCD question wrong?
Review app Engine standard runtime, then practise related PCD questions on the same topic to reinforce the concept.
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?
App Engine standard runtime
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Last reviewed: Jul 4, 2026
This PCD practice question is part of Courseiva's free Google Cloud 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 PCD exam.
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