Content region not expanding

This is a core issue. Don't ask me to explain it, it's too complicated. Read all the comments in the related issue (especially closer to the end).

I found a post with a proposed solution. I tried the concept out in the Bootstrap page.html.twig file, and it seems to work.

Current Bootstrap page.html.twig file, around line 131:

{# Content #}
{%
  set content_classes = [
    page.sidebar_first and page.sidebar_second ? 'col-sm-6',
    page.sidebar_first and page.sidebar_second is empty ? 'col-sm-9',
    page.sidebar_second and page.sidebar_first is empty ? 'col-sm-9',
    page.sidebar_first is empty and page.sidebar_second is empty ? 'col-sm-12'
  ]
%}

With added checks, to see if the regions are empty or not:

{# Content #}
{%
  set content_classes = [
    page.sidebar_first|render|striptags|trim and page.sidebar_second|render|striptags|trim ? 'col-sm-6',
    page.sidebar_first|render|striptags|trim and page.sidebar_second|render|striptags|trim is empty ? 'col-sm-9',
    page.sidebar_second|render|striptags|trim and page.sidebar_first|render|striptags|trim is empty ? 'col-sm-9',
    page.sidebar_first|render|striptags|trim is empty and page.sidebar_second|render|striptags|trim is empty ? 'col-sm-12'
  ]
%}

It looks clunky, but an empty sidebar_second is no longer printed out.

Similarly, if you don't want to show empty blocks, update block.html.twig:

{% if content|render|striptags|trim %}
  <section{{ attributes.addClass(classes) }}>
    {{ title_prefix }}
    {% if label %}
      <h2{{ title_attributes.addClass('block-title') }}>{{ label }}</h2>
    {% endif %}
    {{ title_suffix }}

    {% block content %}
      {{ content }}
    {% endblock %}
  </section>
{% endif %}

You cannot use the striptags Twig filter as it would strip out all valid HTML that's in the content as well, if it isn't actually empty.

Like I said, this is a core bug... one that is very complex and complicated.

Thanks for commenting. What do you do, to avoid printing out empty regions and blocks?

Nothing.... that's why it's a major core bug.

As @markcarver warned, I used this method and now debugged it for a day to find why my block is not visible:
<drupal-render-placeholder callback="Drupal\block\BlockViewBuilder::lazyBuilder" arguments="0=eventregistrationform&amp;1=full&amp;2" token="afb5cea2"></drupal-render-placeholder>
I was expecting the region to have actual html in it but Drupal switches from html to placeholders according to whatever the internal mechanics are.

3 years ago and that bug still isn't fixed? Or have I missed something?

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