Update to Drupal 8.0.0-beta15. For more information, see: https://www.drupal.org/node/2563023

core/config/schema/core.data_types.schema.yml

@@ -491,7 +491,7 @@ field.value.string_long:
 # Schema for the configuration of the URI field type.
 
 field.storage_settings.uri:
-  type: mapping
+  type: field.storage_settings.string
   label: 'URI settings'
   mapping:
     max_length:
@@ -646,10 +646,10 @@ field.field_settings.integer:
       type: integer
       label: 'Maximum'
     prefix:
-      type: string
+      type: label
       label: 'Prefix'
     suffix:
-      type: string
+      type: label
       label: 'Suffix'
 
 field.value.integer:
@@ -684,10 +684,10 @@ field.field_settings.decimal:
       type: float
       label: 'Maximum'
     prefix:
-      type: string
+      type: label
       label: 'Prefix'
     suffix:
-      type: string
+      type: label
       label: 'Suffix'
 
 field.value.decimal:
@@ -715,10 +715,10 @@ field.field_settings.float:
       type: float
       label: 'Maximum'
     prefix:
-      type: string
+      type: label
       label: 'Prefix'
     suffix:
-      type: string
+      type: label
       label: 'Suffix'
 
 field.value.float:

core/config/schema/core.entity.schema.yml

@@ -160,6 +160,17 @@ field.widget.settings.string_textarea:
       type: label
       label: 'Placeholder'
 
+field.widget.settings.uri:
+  type: mapping
+  label: 'URI field'
+  mapping:
+    size:
+      type: integer
+      label: 'Size of URI field'
+    placeholder:
+      type: label
+      label: 'Placeholder'
+
 field.widget.settings.email_default:
   type: mapping
   label: 'Email field display format settings'