Drupal 8.x

I have tried to update drupal 8.0.5 to 8.4.2 but no success. I have tried it a couple of different ways. Direct update didn't work, so i tried going to 8.1.0 then 8.2.0, 8.3.0, 8.4.2, but it crashed when updating from 8.2.0 to 8.3.0. So i tried (found a suggestion) to 8.2.5 and also 8.2.8 but none of the updates worked. 
This was all done with option 2. https://www.drupal.org/docs/8/update/update-core-option-2

I created a directory "DrupalForm" with files; DrupalForm.info.yml and DrupalForm.routing.yml. I also created the directories "src" and "Form" within "src" and a php file called "Applicationform.php" in the "Form" folder with all the requisite function calls and references. My routing.yml file is as follows:

 drupalform.form:
  path: '/Applicationform'
  defaults:
   _title: 'Application Form'
   _form: '\Drupal\DrupalForm\Form\Applicationform'
  
  requirements:
  
   _permission: 'access content'
  

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I am porting my module to Drupal 8:
https://www.drupal.org/project/taxonomy_facets

I want to declare router and pass unknown  / unlimited number of arguments to it, but cannot find out how to, for example:
 

Hi everyone, I'm very new in Drupal. 

I'm creating a theme and I cannot show content in a page different from the front one. My code right now is the following: 

<div id="content">
    {% if front_page %}
        {% block content %}{% endblock %}
    {% else %}
        {{ page.content }}
    {% endif %}
</div>

I'm editing the block "content" in my page--front.hmtl.twig and it shows perfectly. But when I switch from myweb to myweb/simple only the header is shown.