Fail: Call to undefined method stdClass::get()

Hi at all,
Since a few weeks I'm facing problems with Frontend Login.
As soon as i try to logon, i got this Error-Message

Error 0: Call to undefined method stdClass::get()

In the backend i see me logged in with a red cross at "Site"



My Configuration looks like this (Sorry German )



I tried different PHP-Version, currently 7.2.6 is activated. I have no idea where to search for a solution. ARK-Editor is installed (I found some errors with this component, but not related to Get()-Function. In the German Joomla User Forum i started the same Question ( forum.joomla.de/thread/6000-login-fehler...class-get/#post40962 ) , and there comes up, it could be related to the Template. Therefore i ask here.

I'm a really "regular /normal" User, not a PHP-Expert . I have no idea, because Get()-Function ist more or less everywhere used, and the Site works properly,... without frontend login. Thanks for reading and thinking about that.

Regards Rainer

Hi there,
1.) The red cross in the backend is a button and not an error
2.) Which extensions are installed ?

Otherwise provide us userdata and url to check if it is a tempalte problem or not.
Please use the secret button to hide personal data.

Hi there

I know the button is to unlog the User from backend
It is ab crazy, in the meanwhile i found out, the problem occurs first, if username and password is correct.
If one of them is not correct, another Login page comes up "Passwort or username is not correct". By entering correct username and password, the login works without a failure. But not all menupoints are working well. At some menupoint the page will be displayed correct, on some menupoints i got the Error as described.
Completeley strange.
The URL is www.mgow.ch/neu
I faced the same Problem with another Subsite www.mgwo.ch/f4c . This is a blank new installatioin, wher only some Extensions are installed. ARK-Editor, Breezing Forms and Smart Slider 3. Here i disabled the Login Module, because it is not realy necessary. The Template ist even ICE from Joomlaplates.
[secret]Username: josu_2018
Password: 2018_Josu_Check
This is a SuperUser Account. Valid until 20.7. 6:00 PM. Take Care [/secret]

Regards Rainer

Sorry I have no access.
BTW You can mail me user data too.
support@joomlaplates.com

Hi there

I told valid until 20.7
Activated described user again. But i think, it is not a template based problem. Yesterday i renamed the template "mod_login" and forced to use standard Joomla Login Modul instead: Same Problem came up.
So, from my point of view, there is something wrong more indepth. But i have no idea where to search, because the problem occure www.mgow.ch/neu and www.mgow.ch/f4c . The last one is blank setup from december last year with only a few extension (ARK Media Prof., Breezing Form Pro, Smart Slider 3). This extension are also used at www.mgow.ch/neu .

Thanks for any help
Rainer