PHP-Error

Most Common PHP Error Messages and Their Causes

Here are some of the most well-known PHP error messages and the most common causes behind them: 

Parse Error: Syntax Error

Cause: 
This error occurs when there is a syntax error in the PHP code. Common causes include: 

• Missing semicolons (;) at the end of a statement. 
• Unclosed brackets ((), {}, []). 
• Incorrect use of quotation marks (" or '). 

Fatal Error: Call to Undefined Function

Cause: 
This error occurs when the code attempts to call a function that either doesn’t exist or is misspelled. Common reasons include: 

• Typo in the function name. 
• The function is defined in another PHP file that hasn’t been included. 
• The required PHP extension is not installed or activated. 

Warning: Cannot Modify Header Information – Headers Already Sent

Cause: 
This warning occurs when the server tries to send HTTP headers after output (e.g., HTML or echo) has already been sent. Common causes include: 

• Whitespace or new lines before the <?php tag or after a closing ?> tag. 
• Output of content (e.g., with echo or print) before using header() or setcookie(). 

Fatal Error: Allowed Memory Size Exhausted

Cause: 
The PHP script required more memory than allowed by the PHP configuration. This often occurs in large loops, big file processing, or poorly optimized queries. 

Fatal Error: Maximum Execution Time Exceeded

Cause: 
The script has exceeded the maximum allowed execution time. This occurs in long-running processes like large database queries or processing large files. By default, the maximum execution time is set to 30 seconds. 

Notice: Undefined Variable

Cause: 
This notice is displayed when trying to access a variable that hasn't been defined yet. This often happens when a variable is used before it has been initialized. 

Deprecated: Function Name is Deprecated

Cause: 
The used function is deprecated and will not be supported in future versions of PHP. It should be replaced with a more modern function.