If we go to node view we receive non catchable MethodNotAllowedException.
Step to reproduce:
1. Install module rest.
2. Install module language.
3. Install module page_manager(Seams that this step can be excluded).
4. Create some language.
5. go to /admin/config/regional/language/detection and check Account administration pages.
6. Go to user edit page and set some language in "Administration pages language".
7. Go to node view.
You will receive:
Symfony\Component\Routing\Exception\MethodNotAllowedException: in Symfony\Component\Routing\Matcher\UrlMatcher->match() (line 97 of vendor/symfony/routing/Matcher/UrlMatcher.php).
Drupal\Core\Routing\UrlMatcher->finalMatch(Object, Object) (Line: 152)
Symfony\Cmf\Component\Routing\NestedMatcher\NestedMatcher->matchRequest(Object) (Line: 258)
Symfony\Cmf\Component\Routing\DynamicRouter->matchRequest(Object) (Line: 185)
Symfony\Cmf\Component\Routing\ChainRouter->doMatch('/node/212', Object) (Line: 155)
Symfony\Cmf\Component\Routing\ChainRouter->matchRequest(Object) (Line: 89)
Drupal\Core\Routing\AccessAwareRouter->matchRequest(Object) (Line: 138)
Drupal\Core\Routing\AccessAwareRouter->match('/node/212') (Line: 139)
Drupal\user\Plugin\LanguageNegotiation\LanguageNegotiationUserAdmin->isAdminPath(Object) (Line: 109)
Drupal\user\Plugin\LanguageNegotiation\LanguageNegotiationUserAdmin->getLangcode(Object) (Line: 191)
Drupal\language\LanguageNegotiator->negotiateLanguage('language_interface', 'language-user-admin') (Line: 136)
Drupal\language\LanguageNegotiator->initializeType('language_interface') (Line: 223)
Drupal\language\ConfigurableLanguageManager->getCurrentLanguage() (Line: 84)
Drupal\language\EventSubscriber\LanguageRequestSubscriber->onKernelRequestLanguage(Object, 'kernel.request', Object) (Line: 116)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('kernel.request', Object) (Line: 120)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 62)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 62)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 53)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 103)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 82)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 55)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 632)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)