As christogeretz said, try with the custom menu.
Also please note that if you don’t disable the canonical url,
your thank you page will be very easily found by searching.
So if you want to hide your thankyou page, it would be a good idea
to disable the canonical url.
To disable it, drop the line of code in your functions.php
remove_filter(‘template_redirect’, ‘redirect_canonical’);
or use the plugin.
http://ww.wp.xz.cn/extend/plugins/disable-canonical-url-redirects/
It seems your functions.php might have an error.
Maybe check functions.php and see the code at line 15
what the issue would be.
If you are not sure, you can post the code bit (line 15)
and we can check what the issue would be.
It seems it was Events Calendar.
Have you added the function somewhere in your theme files?
<?php sidebarEventsCalendar();?>
Go to Plugins page (on admin) and see if the plugin is removed.
And go to Widgets page and remove the calendar widget from the sidebar.
If it still didn’t fix, please let us know what’s the plugin name you are using.
