Drupal 8.x

[Solved] I had been trying to figure out how to display
a Drupal 8 version of the D7 "Book Navigation" menu block,
since it was not listed anywhere on the "Block layout" page;
not even under the Region-heading 'Disabled'.

See the comment below,
"D8 - Display missing blocks using any 'Place block' button",
for more info.

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Note: This posting has been substantially changed since VM's kind posting in comment #1. (2015.12.29)

Hi

Running 8.01 and cannot get any TAR files processed by this D8 installation.
Installing the same as a ZIP file is okay though!

1. When updating a module (updating Mayo theme in this case), I get the following error:

An AJAX HTTP error occurred.
HTTP Result Code: 500
Debugging information follows.
Path: /batch?id=7&op=do_nojs&op=do
StatusText: Internal Server Error
ResponseText: 

Please note that the ResponseText was blank (I have not missed it out).

Hello!

I have made a view block and the machine name of the view is promoted_slideshow. I want to extend the style of the view block rows so I created a new template file, named block--views-block--promoted-slideshow-block-1.html.twig

Inside it is written the following:

{% extends "/core/modules/block/templates/block.html.twig" %}

{% block content %}
{{ content }}
{% endblock %}

How can I separately style each row of the content? And look for example like this, which of course doesn't work:

Hi...
I've a newly created website about mobile apps on red technology & it's now running on wordpress. I'm not a drupal expert but it's been decided to take it into drupal 8. So I need suggestions from expert about how can I make that happen by keeping the existing content safe?
Thanks in advance. Please help.

When upgrading with the Drupal migrate module i first got problems with 'url-aliases'. There wher more then 56,000 and the migrate module stops with an error. I then truncate te table and start again. Now I'm migrating about 25,000 nodes and got also an error. When it stops and i rerun the migrate module i see that now the nodes are migrated one by one...

Currently upgrading Nodes (adresarchief) (51 of 121 total tasks)
Continuing with Nodes (adresarchief) (processed 1 item)
Continuing with Nodes (adresarchief) (processed 1 items)

I have some html content, it comes from a external library so i can not change it, it has many <span> and <div> tags with attributes like:
<span style="color: #0000ff;">
But when i use:

$render = array(
  '#markup' => $myhtmlcontent,
)

In a render array, drupal strips the attibutes, it keed just<span> without the style.