[SOLVED] Unknown modifier '%' error on phplist-plugin-viewbrowser

Hi there!
I am trying this plugin GitHub - bramley/phplist-plugin-viewbrowser: Plugin for phplist 3.x to view an email in a browser
The only issue is that is showing several errors when someone uses the link.

Here they are:

Sorry a software error occurred:
Please report a bug when reporting the bug, please include URL and the entire content of this page.

Warning: preg_match(): Unknown modifier ‘%’ in /home/username/public_html/newsletter/admin/lib.php on line 1930
phpList version 3.3.1

Sorry a software error occurred:
Please report a bug when reporting the bug, please include URL and the entire content of this page.

Warning: preg_match(): Unknown modifier ‘%’ in /home/username/public_html/newsletter/admin/lib.php on line 1930
phpList version 3.3.1

Any idea what is wrong? how to solve it?

Best regards!
Luciano

Here Bramley hit the key, it was a / used in atributes and phplist not managing it properly…