Drupal 8.x

Every time I create a field of the type Text (Plain), when I try to access "Manage Display", I get a 500 error page. I have that in comment, content, but also user accounts settings. 

I even made a fresh install, added all my modules and it does it again. Is there ANY solutions that I can try to see which one is making the error? I have too many of them to just do one by one. 

Is it possible to place my main menu in the Bartik 8.7.9 theme 'on top' (like in https://www.drupal.org/forum)?

Also, how-to create the same search and login like in https://www.drupal.org/forum?

If not, are there other themes where this is possible?

I have several issues here;

- I can't use the Store Locator module because it's not compatible with Drupal 8

- I can't use Google Maps because the organisation I work for is concerned that we'll be charged for it

- I'm trying to use Geofield and Leaflet but when I try to enter the latitude and longitude I get an error saying "POINT (146.813299 -19.262214) is not a valid geospatial content."

Hi,

1 - Hosting company migrated a copy of my Drupal 8 site to a new server

2 - This was along with 6 non-Drupal sites

3 - I am testing them on the new server through my local HOSTS file

4 - All non-Drupal sites are reachable and test fine

5 - The Drupal site returns: Forbidden

6 - This Drupal 8 site is the only Drupal site I have built (I have no extensive Drupal experience)

We have many Views and Views displays. Over 3 years of building the site we have many displays that are not being used. We would like to delete them and clean up the view but are concerned that a display might be used in the site. Is there a way of determining if a views display is being used on the site? I thought of different ways to check this: