🎯 PHP Error Handling – Interview Questions
🟢 Basic Level
1. What is error handling in PHP?
Answer:
Error handling is the process of detecting, managing, and responding to runtime or syntax errors in a PHP script.
2. What are the types of errors in PHP?
Answer:
- Notice
- Warning
- Fatal Error
- Parse Error
- Deprecated Error
3. Difference between Warning and Fatal Error?
| Warning | Fatal Error |
|---|---|
| Script continues | Script stops |
| Non-critical | Critical issue |
4. What is error_reporting()?
Answer:
It defines which errors should be reported.
error_reporting(E_ALL);5. How to display errors in PHP?
ini_set('display_errors', 1);
error_reporting(E_ALL);🟡 Intermediate Level
6. What is Exception Handling?
Answer:
A mechanism to handle runtime errors using try, catch, and throw.
7. Explain try-catch block.
try {
// risky code
} catch (Exception $e) {
echo $e->getMessage();
}8. What is the use of throw?
Answer:
It is used to generate an exception manually.
9. Difference between Error and Exception?
| Error | Exception |
|---|---|
| System-level issue | Application-level issue |
| Cannot always be handled | Can be handled using try-catch |
10. What is Throwable in PHP?
Answer:
Base interface for both Error and Exception (PHP 7+).
🔵 Advanced Level
11. What is a custom error handler?
Answer:
A user-defined function to handle errors using set_error_handler().
set_error_handler("myErrorFunction");12. What is trigger_error()?
Answer:
Used to create a user-defined error.
trigger_error("Custom error", E_USER_WARNING);13. How to log errors in PHP?
error_log("Error message", 3, "error.log");14. What is the difference between die() and exception?
| die() | Exception |
|---|---|
| Stops script immediately | Can be handled |
| No recovery | Recovery possible |
15. How to handle database errors in PHP?
Answer:
Using try-catch with PDO or checking connection errors.
16. What is PDO exception mode?
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);17. What are best practices for error handling?
Answer:
- Hide errors in production
- Log errors instead
- Use try-catch blocks
- Validate inputs
- Use custom handlers
🔥 Scenario-Based Questions
18. What will happen in this code?
echo 10/0;
Answer:
Division by zero → Warning or Error (PHP version dependent)
19. How will you handle API failure?
Answer:
- Use try-catch
- Check response status
- Log errors
- Show user-friendly message
20. How do you debug a white screen error?
Answer:
- Enable error reporting
- Check logs
- Use
var_dump() - Check syntax errors
🚀 Pro Interview Questions
21. Can we catch fatal errors in PHP?
Answer:
Not directly, but can use:
register_shutdown_function()
22. What is shutdown function?
register_shutdown_function(function() {
print_r(error_get_last());
});23. How to convert errors into exceptions?
set_error_handler(function($errno, $errstr) {
throw new ErrorException($errstr, 0, $errno);
});24. What is stack trace?
Answer:
A report of function calls leading to an error.
25. How to handle errors in production?
Answer:
- Disable display_errors
- Enable logging
- Monitor logs
- Use centralized error tracking
🎯 Bonus Tip (Interview Hack)
If interviewer asks:
👉 “How do you handle errors in real projects?”
Say:
“I use try-catch for critical operations, enable logging instead of displaying errors in production, use custom error handlers, and monitor logs for debugging.”
