Redirect problem on checkout

Hello everyone,

since an update I have following problem with Jigoshop:

When I press the “Place order” button on check out I get to a new page and receive the error:
Warning: Cannot modify header information – headers already sent by (output started at …/themename/header.php:3) in …/wp-includes/pluggable.php on line 1124.

I’ve tried to track the problem: It’s caused by the function wp_redirect() which is called by shortcodes/checkout.php. So wp_redirect() seems to be called after the first output of the theme started. Has there been any changes in action hooks etc.?

I’m looking forward to your suggestions. Thanks in advance 😉

https://ww.wp.xz.cn/plugins/jigoshop/