Where does PHP's error log reside in XAMPP?
Solution 1:
\xampp\apache\logs\error.log, where xampp is your installation folder.
If you haven't changed the error_log setting in PHP (check with phpinfo()), it will be logged to the Apache log.
Solution 2:
I found it in:
\xampp\php\logs\php_error_log
Solution 3:
You can also open the XAMPP control panel and click on the button Logs:
Solution 4:
For Mac users, XAMPP version 1.7.3:
/Applications/XAMPP/xamppfiles/logs/error_log