Page Manager Issues on my Installation

Today I downloadet the latest sitecake-2.4.1-whitelabel and tested the Pagemanager. I am wondering that the Pagemanager does not work at all. It opens up yes… but first of all I saw, that Pagemanager can’t handle HTML special chare. It shows up an ü like follows für. I also try to change the Page title within the -HTML PAGES- section using the -Details- tool. After type in something into Page Title and hit -Publish- nothing happens, the Publish button keeps on spinning- nothing gets stored. I tryed all other funktionality but unfortunately nothing works for me.
I am using PHP7 no special PHPIni seted up.
Does anybody run into the same like me?
I can not go on and I do not know where to start

One strange issue after installing beta - Notice: Use of undefined constant QUERY_STRING - assumed 'QUERY_STRING' in file [SITE]/sitecake/2.4.0dev/src/Sitecake/Page.php(539) : eval()'d code on line (#1)
And SiteCake doesn’t work
After changing $app[‘debug’] = true; Notice dissapeared and everything works fine…

@pyotr Sitecake is evaluating php pages so I assume that you are using QUERY_STRING constant somewhere in your php page that is not previously defined.

@predragleka yep you are right - thank you

@predragleka i use it like this to rule with UTM labels:
<?php $utm = $_SERVER[QUERY_STRING] ? '?'.$_SERVER[QUERY_STRING] : ''; ?>

Just use it with quotes
$_SERVER['QUERY_STRING']

@predragleka Thank you!

@Sitebake I will create a ticket with your issues. We need access to your website to see why this issues are occuring in your environment.