Title: Cannot modify header information– serious problem! Last modified: August 31, 2016 --- # Cannot modify header information– serious problem! * Resolved [amin.ardani](https://wordpress.org/support/users/aminardani/) * (@aminardani) * [10 years, 4 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-serious-problem/) * hi, i have a serious problem today, i can not login in my wordpress admin panel when i type “www.malardmushrooms.com/wp-admin” i see this error: * Warning: Cannot modify header information – headers already sent by (output started at /var/www/vhosts/malardmushrooms.com/httpdocs/wp-content/plugins/w3-total-cache/ inc/functions/compat.php:1) in /var/www/vhosts/malardmushrooms.com/httpdocs/wp- includes/pluggable.php on line 1228 * and i follow the FAQ_Troubleshooting but my problem was not solved. have anyone other idea??? help PLEASE Viewing 5 replies - 1 through 5 (of 5 total) * [Allison Tarr](https://wordpress.org/support/users/allisonplus/) * (@allisonplus) * [10 years, 4 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-serious-problem/#post-6929270) * Hi Amin Ardani, * This is usually due to spaces, new lines, or other “extras” at opening/closing PHP file tag. Have you been modifying any of your php files or perhaps adding new plugins? * Thread Starter [amin.ardani](https://wordpress.org/support/users/aminardani/) * (@aminardani) * [10 years, 4 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-serious-problem/#post-6929322) * Thanks for attention dear allisonplus i add the “W3 Total Cache 0.9.4.1” plugin and after two or three days i see that error. the important notice is that is this website is belonging to the company and i’m just a simple employee!!! i can gave you the password for helping me * Moderator [James Huff](https://wordpress.org/support/users/macmanx/) * (@macmanx) * [10 years, 4 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-serious-problem/#post-6929324) * > i can gave you the password for helping me * Please do not do that: [https://codex.wordpress.org/Forum_Welcome#The_Bad_Stuff](https://codex.wordpress.org/Forum_Welcome#The_Bad_Stuff) * If you’d like to give someone direct access, please try [http://jobs.wordpress.net/](http://jobs.wordpress.net/) or [http://directory.codepoet.com/](http://directory.codepoet.com/) and do not accept any hire or direct access offers posted to these forums. * As for your problem, you have unexpected whitespace (either a space or an entire line) on line 1 of the `/wp-content/plugins/w3-total-cache/inc/functions/compat. php` file. See [this guide](https://codex.wordpress.org/FAQ_Troubleshooting#How_do_I_solve_the_Headers_already_sent_warning_problem.3F) for more info. * Alternatively, replacing the file with one from a fresh download may resolve the issue. * Thread Starter [amin.ardani](https://wordpress.org/support/users/aminardani/) * (@aminardani) * [10 years, 4 months ago](https://wordpress.org/support/topic/cannot-modify-header-information-serious-problem/#post-6929332) * thank you so much dear James.. my error is gone!!!! i’m so worried about this two days! but now it’s solved. i tried to fix the pluggable.php and login.php and config.php but the problem come from another place. exact here: `wp-content/ plugins/w3-total-cache/inc/functions/compat.php` there was just a blank before