Thread:Extension talk:Cite/Error after installing Cite extension

Hello there, i'm running MW V1.19.3, everything worked perfectly after I installed Cite extension, now i get this error x2 on every page:

Warning: Cannot modify header information - headers already sent by (output started at /.../LocalSettings.php:1) in /.../includes/WebResponse.php on line 38

And can't access to my index/home page, the error just show up seven times, please can anybody help me?