Warning – “Cannot Modify Header Information” Error

Andrei Iordache

Andrei Iordache

WordPress Developer

🚀 I Help People Get Found Online | WordPress Development, Core Web Vitals, Security&Maintenance

Warning – “Cannot Modify Header Information” Error

This happens when the error is triggered due to a broken code within your page’s header. The message, for instance, appears like this:

Warning: Cannot modify header information - headers already sent by (output started at /yoursite/wp-config.php:1) in /yoursite/wp-includes/pluggable.php on line 1251 

Warning: Cannot modify header information - headers already sent by (output started at /yoursite/wp-config.php:1) in /yoursite/wp-includes/pluggable.php on line 1254

Solutions:

1st solution

The warning cannot modify header information – headers already sent by error can be solved in different ways. First, go to wp-config.php and add this code on the first line:

ob_start(); 

error_reporting(0);

Clean the browser’s cache (if you have any cache plugin installed, try to flush it) and see if the issue was solved.

2nd solution

The solution for me was the windows locale wasn’t on UTF8, and unzipping the files seems to have screwed things up.

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Lusi StudiosLusi Studios
15:32 22 Jun 22
Andrei did an amazing job! He helped in a very rushed time and he excelled at everything. Thanks again!
I am grateful and I would to thank Websites Seller for their support in site recovery and site transfer. Websites Seller just saved my business. Thank you!
Wouter GhysensWouter Ghysens
11:52 10 Sep 21
Looking for a Wordpress transfer from site A to site B, I found back Andrei from Wesites Seller on Google.He was very proactive in his approach, came with hundreds of ideas and lifetime experiences from other migrations. He knows the wordpress, the hosting and php database as the back of his pocket.And we worked out this migration very smooth. Together we solved it, and myself and my business are very pleased with his approach.100% recommendation & kudo's from out of Belgium!
Ioachim CiobanuIoachim Ciobanu
18:39 14 Jul 21
Websites Seller built my resume site. Deliverables were quickly completed, and I was asked for my feedback at each stage of development. All feedback I gave was implemented in a short time.Another great thing is that he comes with smart solutions, regarding stuff which I didn't initially think of (site security, Google site speed optimization and so on). Basically, he was great, staying in touch, keeping me updated and paid attention to what was most important for my site.Overall, I am very happy with the work done. I highly recommend this developer!
K CollinsK Collins
09:11 19 May 21
I needed help with website speed - to improve my core web vitals - without compromising the usability of my site. Andrei was extremely responsive, proactive and fast. And more importantly, he increased by website speed. Highly recommend him, and I will be using him going forward on all my projects.
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