Quick Answer
The correct approach is to use a try-except block catching FileNotFoundError, as this directly handles the specific exception raised when a file does not exist. This is the most Pythonic method because it follows the EAFP (Easier to Ask for Forgiveness than Permission) principle, where you attempt the operation and gracefully handle the failure rather than checking conditions beforehand with cluttered if-statements. On the Certified Associate Python Programmer PCAP exam, this question tests your understanding of exception hierarchy and idiomatic error handling—a common trap is catching the overly broad Exception or OSError, which can mask unrelated bugs. Remember that FileNotFoundError is a subclass of OSError, so catching the specific type keeps your code precise and maintainable. A useful memory tip: think "EAFP first, LBYL last"—always prefer try-except for file operations over os.path.exists checks, as the file could be deleted between the check and the open call.
This PCAP practice question tests your understanding of exceptions and file i/o. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 writes a script to read a configuration file that may not exist. The script should handle the error gracefully and continue. Which approach is most Pythonic?
Use a try-except block catching FileNotFoundError
EAFP; clean and recommended for this scenario.
Use a try-except block catching OSError
Why wrong: Too broad; catches more than necessary.
Use os.path.exists to check, then open if it exists
Why wrong: LBYL approach; prone to race conditions and less Pythonic.
Use an if statement to check file size
Why wrong: Does not handle missing file; incorrect logic.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Use a try-except block catching FileNotFoundError
Option A is correct because it directly catches the specific `FileNotFoundError` exception, which is a subclass of `OSError` and is raised when a file does not exist. This approach follows the Pythonic principle of EAFP (Easier to Ask for Forgiveness than Permission), allowing the script to attempt the operation and handle the failure gracefully without redundant checks.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Use a try-except block catching FileNotFoundError
Why this is correct
EAFP; clean and recommended for this scenario.
Related concept
Read the scenario before looking for a memorised answer.
Use a try-except block catching OSError
Why it's wrong here
Too broad; catches more than necessary.
Use os.path.exists to check, then open if it exists
Why it's wrong here
LBYL approach; prone to race conditions and less Pythonic.
Use an if statement to check file size
Why it's wrong here
Does not handle missing file; incorrect logic.
Common exam traps
Python Institute often tests the distinction between catching a specific exception (`FileNotFoundError`) versus a broader parent exception (`OSError`), and the trap here is that candidates may choose the broader catch thinking it is safer, without realizing it can mask other critical errors.
Detailed technical explanation
In Python, `FileNotFoundError` is a subclass of `OSError` (specifically `OSError` with errno 2, `ENOENT`), introduced in Python 3.3 to provide more granular exception handling for file operations. The EAFP style is preferred in Python because it avoids race conditions inherent in LBYL checks and leads to cleaner, more readable code, especially in concurrent or multi-threaded environments where file system state can change between operations.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
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FAQ
Exceptions and File I/O — This question tests Exceptions and File I/O — Read the scenario before looking for a memorised answer..
The correct answer is: Use a try-except block catching FileNotFoundError — Option A is correct because it directly catches the specific `FileNotFoundError` exception, which is a subclass of `OSError` and is raised when a file does not exist. This approach follows the Pythonic principle of EAFP (Easier to Ask for Forgiveness than Permission), allowing the script to attempt the operation and handle the failure gracefully without redundant checks.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A developer writes a script that reads a configuration file. If the file does not exist, the program should print an error and continue. Which code snippet correctly implements this behavior?
easyWhy A: Option A is correct because it uses a `try` block to attempt opening the file and catches only `FileNotFoundError`, which is the specific exception raised when the file does not exist. This allows the program to print an error and continue execution without crashing, precisely matching the requirement.
Variation 2. A developer writes a function that reads a configuration file and returns its contents as a string. The file might not exist. Which exception should be caught to handle a missing file?
easyWhy A: Option A is correct because `FileNotFoundError` is a built-in exception in Python that is raised when a file or directory is requested but does not exist. In Python 3, file-related I/O errors are organized under `OSError` with specific subclasses, and `FileNotFoundError` is the precise exception for a missing file, making it the most appropriate catch for this scenario.
Variation 3. A developer writes a function that reads a file and processes its content. The function should handle the case where the file does not exist without catching other I/O errors. Which exception should be caught?
easyWhy D: Option D is correct because `FileNotFoundError` is a specific subclass of `OSError` that is raised exactly when a file or directory is requested but does not exist. By catching only `FileNotFoundError`, the function handles the missing-file scenario without masking other I/O errors such as permission issues or disk failures, which is the precise requirement stated in the question.
Last reviewed: Jun 30, 2026
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