What is PHP Output Buffering?

What is PHP Output Buffering?

The error described below is increasingly common, especially on websites running WordPress. It occurs when PHP attempts to modify the HTTP headers but fails because another file has already sent them. 

By default, PHP uses implicit buffering, which means headers are sent to the browser as soon as they are generated. 

This issue can also arise from whitespace in a file, preventing the file from being parsed correctly.

Warning: Cannot modify header information - headers already sent by (output started at /home/sites/12/b/3/1373620/public_html/wp-content/themes/twentytwentythree/functions.php:121

How to fix PHP Output Buffering? 

To address this error, access the PHP configuration for your package and enable output buffering. This switches the buffering mode to explicit, allowing headers to be stored and only sent to the browser after all processes are complete.

Are there any limitations to PHP Output Buffering? 

While output buffering is highly beneficial in many situations, there are times when it's important to assess its appropriateness. 

Such scenarios may involve processing a large volume of data, needing real-time output, or managing dynamic site content.