The correct approach is to wrap the log write in a try/except that catches OSError and writes to stderr as a fallback. This works because OSError is the parent class for disk-full conditions and other file system errors, allowing you to gracefully handle the failure without crashing the main application. By isolating the logging operation inside a targeted exception handler, you adhere to the principle of handling exceptions only where you can meaningfully recover, and the fallback to stderr ensures the error is still reported. On the Certified Associate Python Programmer PCAP exam, this tests your understanding of exception hierarchy and graceful degradation in I/O operations—a common trap is catching a too-broad Exception or ignoring the error entirely, which would either mask bugs or leave the application vulnerable. Remember the mnemonic: “Log with try, fallback to stderr, or your app will err.”
PCAP Exceptions and File I/O Practice Question
This PCAP practice question tests your understanding of exceptions and file i/o. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 building a logging system that writes logs to a file. The system should handle disk-full situations gracefully without crashing the main application. Which approach is appropriate?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Wrap the log write in a try/except that catches OSError and writes to stderr as fallback.
Option D is correct because it uses a targeted try/except block around only the log write operation, catching OSError (which includes disk-full conditions) and falling back to stderr. This prevents the main application from crashing while still reporting the error, adhering to the principle of handling exceptions at the point where they occur and only when you can meaningfully recover.
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.
✗
Check disk space before each write; if low, skip logging.
Why it's wrong here
Checking disk space before each write is inefficient and not thread-safe; may still fail.
✗
Wrap the entire application in a try/except that catches all exceptions.
Why it's wrong here
Too broad; hides other bugs and doesn't provide a targeted fallback.
✗
Let the OSError propagate to the main program's exception handler.
Why it's wrong here
May crash the main application; not graceful.
✓
Wrap the log write in a try/except that catches OSError and writes to stderr as fallback.
Why this is correct
Catches disk-full errors and logs to stderr, keeping app running.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Python Institute often tests the distinction between catching overly broad exceptions (Option B) versus catching specific exceptions (Option D), and the trap here is that candidates may think 'catching all exceptions' is a safe catch-all, but it actually hides programming errors and violates Python best practices.
Detailed technical explanation
How to think about this question
Under the hood, Python's OSError is a base class for file-related errors (e.g., IOError, PermissionError, FileNotFoundError). When a disk-full condition occurs, the write() call raises an OSError with errno set to ENOSPC (28 on Linux). By catching OSError specifically, the developer can inspect errno to differentiate disk-full from other errors, and writing to stderr (file descriptor 2) is a standard fallback that does not depend on the full disk. In real-world systems like web servers or daemons, this pattern is used to ensure critical services continue running even when logging fails.
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 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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Exceptions and File I/O — This question tests Exceptions and File I/O — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Wrap the log write in a try/except that catches OSError and writes to stderr as fallback. — Option D is correct because it uses a targeted try/except block around only the log write operation, catching OSError (which includes disk-full conditions) and falling back to stderr. This prevents the main application from crashing while still reporting the error, adhering to the principle of handling exceptions at the point where they occur and only when you can meaningfully recover.
What should I do if I get this PCAP 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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