Warning: Cannot modify header information - headers already sent by (output started at /home/test/domains/test.nl/public_html/wp-content/themes/mugen/engine/theme-scripts.php:1) in /home/test/domains/test.nl/public_html/wp-content/plugins/woocommerce/classes/class-wc-session-handler.php on line 63
出现这样的情况的原因很多，比如：
1、<?php 或 ?> 前面有空白符
2、<?php 前面有html代码
3、文件不是无BOM的UTF8编码等
*上的文章：
http://*.com/questions/8028957/how-to-fix-headers-already-sent-error-in-php/8028987#8028987