Drupal 8.x

Hello. After upgrading from 8.0.3 to 8.0.4 I am seeing the following error when I load the forum default page (/forum/13).

Does anyone have an idea of why this is happening or point me in the right direction?...

I downloaded and installed the Acquia Dev Desktop. I had been using 7.42 but specified 8.0.2 I used all the defaults and installation was normally but while it was creating the initial website I got this message:

Hi,

I wish to add some field to some menu, to add some specific data to some specific link (images, textes, class..etc) and reuse it in my menu's tamplate.

I found this module for D7 https://www.drupal.org/project/menu_fields, and i was wondering if there a D8 equivalent ? :p
We never know !

How to check if anchor tag in a generated menu link (eg. by main navigation block) has a certain class. For the container li there is the item['attributes']->hasClass() method. However there is nothing of the form item['url']->hasClass(). Can item['url']['urlGenerator'] has something to offer in this regard ?

Hi guys !

I'm overriding blockForm and blockSubmit to create a listbox who can change a value in my function build().

Hello,

I hope this question is not too 'newbie' because I'm not already comfortable with the documentation.

I need an example of a datetime field in a drupal 8 module, particularly for the baseFieldDefinitions() function of the entity class + the buildRow() function of the listing class. I did not find a datetime field used in core modules nor described in this forum.

It would help me a lot.

Thanks