Twig_Error_Loader error I have been running a Drupal 8 site with Pixture Reloaded theme, based on Adaptive theme 
(in my .info file, the corresponding lines are: 

'base theme': at_core

'subtheme type': adaptive_subtheme)

and suddenly, without having done any changes in the site code (just entered content), I get errors of type:  


  The website encountered an unexpected error. Please try again later.
  
  Twig_Error_Loader: Template
  "themes/adaptivetheme/at_core/templates/layout/html.html.twig" is not
  defined (Drupal\Core\Template\Loader\ThemeRegistryLoader: Unable to
  find template
  "themes/adaptivetheme/at_core/templates/layout/html.html.twig" in the
  Drupal theme registry.). in Twig_Loader_Chain->getCacheKey() (line 115
  of vendor/twig/twig/lib/Twig/Loader/Chain.php).


Also, I get similar error when trying to login in the admin, so I cannot clear any cache (if this could help). The site was working the same day earlier and the only thing I have done is enter new content (after having created a new view).

I would appreciate any help.
Eventually, I found out that some updates had been implemented in the theme and some modules and the problem was with the cache, not having been updated, so I run rebuild cache from Drush and the problem was fixed.