[support] Page not found errors Drupal 8

[Roger]

Learning how to create modules and forms I followed the tutorial exactly 
but get Page not found error.
Also it seems the YAML syntax has changed within Drupal 8,
Where
|demo.demo:|
|||path: '/demo'|
|||defaults:|
|||_content: '\Drupal\demo\Controller\DemoController::demo'|
|||_title: 'Demo'|
|||requirements:|
|||_permission: 'access content'

is now-
|
|demo.demo:|
|||path: '/demo'|
|||defaults:|
|||- content: '\Drupal\demo\Controller\DemoController::demo'|
|||- title: 'Demo'
and
|
|||requirements:|
|||- permission: 'access content'
or any other permission causes an error when the caches are cleared.

Can someone please advise what's going on here please?
Thanks
Roger
|