diff --git a/core/modules/block/block.install b/core/modules/block/block.install
index 7e54e3f..305f438 100644
--- a/core/modules/block/block.install
+++ b/core/modules/block/block.install
@@ -124,7 +124,7 @@ function block_update_8003() {
 }
 
 /**
- * Disables blocks that are placed into the "disabled" region.
+ * Disable blocks that are placed into the "disabled" region.
  */
 function block_update_8004() {
   // Find all blocks in the disabled region.
diff --git a/core/modules/block/block.module b/core/modules/block/block.module
index 5b30b4a..eeba0bb 100644
--- a/core/modules/block/block.module
+++ b/core/modules/block/block.module
@@ -145,7 +145,11 @@ function block_rebuild() {
       foreach ($blocks as $block_id => $block) {
         // Disable blocks in invalid regions.
         if (!isset($regions[$block->getRegion()]) && $block->status()) {
-          drupal_set_message(t('The block %info was assigned to the invalid region %region and has been disabled.', ['%info' => $block_id, '%region' => $block->getRegion()]), 'warning');
+          // Do not display the invalid region message if the deprecated
+          // constant was used to disable the block.
+          if ($block->getRegion() !== BlockInterface::BLOCK_REGION_NONE) {
+            drupal_set_message(t('The block %info was assigned to the invalid region %region and has been disabled.', ['%info' => $block_id, '%region' => $block->getRegion()]), 'warning');
+          }
           $block
             ->setRegion(system_default_region($theme))
             ->disable()
diff --git a/core/modules/block/src/Entity/Block.php b/core/modules/block/src/Entity/Block.php
index 1a0c82c..8a1bcd8 100644
--- a/core/modules/block/src/Entity/Block.php
+++ b/core/modules/block/src/Entity/Block.php
@@ -35,7 +35,7 @@
  *     "delete-form" = "/admin/structure/block/manage/{block}/delete",
  *     "edit-form" = "/admin/structure/block/manage/{block}",
  *     "enable" = "/admin/structure/block/manage/{block}/enable",
- *     "disable" = "/admin/structure/block/manage/{block}/disable",
+ *     "disable" = "/admin/structure/block/manage/{block}/disable"
  *   },
  *   config_export = {
  *     "id",