Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

core/modules/aggregator/config/install/core.entity_view_display.aggregator_feed.aggregator_feed.default.yml

@@ -1,31 +1,32 @@
+langcode: en
+status: true
+dependencies:
+  module:
+    - aggregator
 id: aggregator_feed.aggregator_feed.default
 targetEntityType: aggregator_feed
 bundle: aggregator_feed
 mode: default
-status: true
 content:
-  items:
-    weight: 0
   checked:
     type: timestamp_ago
     weight: 1
     settings: {  }
     third_party_settings: {  }
     label: inline
-  image:
-    weight: 2
   description:
     weight: 3
+  feed_icon:
+    weight: 5
+  image:
+    weight: 2
+  items:
+    weight: 0
   link:
     type: uri_link
     weight: 4
     settings: {  }
     third_party_settings: {  }
     label: inline
-  feed_icon:
-    weight: 5
 hidden:
   more_link: true
-dependencies:
-  module:
-    - aggregator

core/modules/aggregator/config/install/core.entity_view_display.aggregator_feed.aggregator_feed.summary.yml

@@ -1,22 +1,22 @@
-id: aggregator_feed.aggregator_feed.summary
-targetEntityType: aggregator_feed
-bundle: aggregator_feed
-mode: summary
-status: true
-content:
-  items:
-    weight: 0
-  more_link:
-    weight: 1
-hidden:
-  link: true
-  checked: true
-  description: true
-  image: true
-  feed_icon: true
+langcode: en
 status: true
 dependencies:
   config:
     - core.entity_view_mode.aggregator_feed.summary
   module:
     - aggregator
+id: aggregator_feed.aggregator_feed.summary
+targetEntityType: aggregator_feed
+bundle: aggregator_feed
+mode: summary
+content:
+  items:
+    weight: 0
+  more_link:
+    weight: 1
+hidden:
+  checked: true
+  description: true
+  feed_icon: true
+  image: true
+  link: true

core/modules/aggregator/config/install/core.entity_view_display.aggregator_item.aggregator_item.summary.yml

@@ -1,20 +1,19 @@
-id: aggregator_item.aggregator_item.summary
-targetEntityType: aggregator_item
-bundle: aggregator_item
-mode: summary
-status: true
-content:
-  timestamp:
-    weight: 0
-hidden:
-  link: true
-  author: true
-  feed: true
-  description: true
+langcode: en
 status: true
 dependencies:
   config:
     - core.entity_view_mode.aggregator_item.summary
   module:
     - aggregator
-    - entity_reference
+id: aggregator_item.aggregator_item.summary
+targetEntityType: aggregator_item
+bundle: aggregator_item
+mode: summary
+content:
+  timestamp:
+    weight: 0
+hidden:
+  author: true
+  description: true
+  feed: true
+  link: true

core/modules/aggregator/config/install/core.entity_view_mode.aggregator_feed.summary.yml

@@ -1,8 +1,9 @@
-id: aggregator_feed.summary
-label: Summary
+langcode: en
 status: true
-cache: true
-targetEntityType: aggregator_feed
 dependencies:
   module:
     - aggregator
+id: aggregator_feed.summary
+label: Summary
+targetEntityType: aggregator_feed
+cache: true

core/modules/aggregator/config/install/core.entity_view_mode.aggregator_item.summary.yml

@@ -1,8 +1,9 @@
-id: aggregator_item.summary
-label: Summary
+langcode: en
 status: true
-cache: true
-targetEntityType: aggregator_item
 dependencies:
   module:
     - aggregator
+id: aggregator_item.summary
+label: Summary
+targetEntityType: aggregator_item
+cache: true