Warning: Cannot modify header information - headers already sent when using ChromePhp.php

Friday, June 28, 2019

Warning: Cannot modify header information - headers already sent when using ChromePhp.php

Answer

I wish to peek into my PHP code to see what is going on to help me rectify some issues. The PHP code is for processing the data from a form. I have tried Chrome Logger http://craig.is/writing/chrome-logger but I can't get it to send me any messages to the browser consloe.

I have built a simple test case:

file ChromeLoggerTest.html




Hi from ChromeLoggerTest.html

file ChromeLoggerTest.php

include 'ChromePhp.php';
$theDate = date("l jS \of F Y h:i:s A");
ChromePhp::log("Hello console using ChromePhp::log from ChromeLoggerTest.php.  The date is: $theDate");
ChromePhp::warn("Hello console using ChromePhp::warn from ChromeLoggerTest.php.  The date is: $theDate");

echo "Hello Browser from ChromeLoggerTest.php. Welcome to my php file to test Chrome Logger.  The date is $theDate 
";
?>

If I type ChromeLoggerTest.html into the browser address bar I obtain in the browser window:

Warning: Cannot modify header information - headers already sent by (output started at /home/d50364/public_html/ChromeLoggerTest.html:3) in /home/d50364/public_html/scripts/ChromePhp.php on line 394

Warning: Cannot modify header information - headers already sent by (output started at /home/d50364/public_html/ChromeLoggerTest.html:3) in /home/d50364/public_html/scripts/ChromePhp.php on line 394

Hello Browser from ChromeLoggerTest.php. Welcome to my php file to test Chrome Logger. The date is Thursday 13th of November 2014 12:35:07 PM

Hi from ChromeLoggerTest.html

There is no output in the console. If I comment out the ChromePhp lines in the PHP file then the errors go away but I do not get any output in the console.

If I type scripts/ ChromeLoggerTest.php into the brwoser address bar I obtain in the browser window and browser console:

Browser:

Hello Browser from ChromeLoggerTest.php. Welcome to my php file to test Chrome Logger. The date is Thursday 13th of November 2014 12:47:13 PM

Browser console:

Hello console using ChromePhp::log from ChromeLoggerTest.php. The date is: Thursday 13th of November 2014 12:47:13 PM
Hello console using ChromePhp::warn from ChromeLoggerTest.php. The date is: Thursday 13th of November 2014 12:47:13 PM

Reading on Stackoverflow there are suggestions about using ob_start(); and ob_flush(); these have not solved my problem.

There are also suggestions that the issue might be caused by whitespace in the files. I have edited them to a single line each and this has not solved my problem.

I have verified that the files are saved without BOM.

Some relevant links:

Warning: Cannot modify header information - headers already sent by ERROR

How to fix "Headers already sent" error in PHP

https://www.geeklog.net/faqman/index.php?op=view&t=38

Setting Up ChromePhp For Wordpress Using Xampp

https://wordpress.org/support/topic/error-cannot-modify-header-information-2

https://github.com/ccampbell/chromephp/issues/15

https://github.com/ccampbell/chromephp

Thank you for taking the time to read this. Any assistance gratefully received.

Answer

Move this: before your because the the new line and the are outputs.