reverted:
--- b/core/config/schema/core.entity.schema.yml
+++ a/core/config/schema/core.entity.schema.yml
@@ -171,17 +171,6 @@
       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'
reverted:
--- b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
+++ a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
@@ -353,11 +353,7 @@
 
         if (!empty($schema['indexes'])) {
           foreach ($schema['indexes'] as $name => $specifier) {
+            $schema_handler->addIndex($table_name, $name, $specifier, $schema);
-            // Check if the index exists because it might already have been
-            // created as part of the earlier entity type update event.
-            if (!$schema_handler->indexExists($table_name, $name)) {
-              $schema_handler->addIndex($table_name, $name, $specifier, $schema);
-            }
           }
         }
         if (!empty($schema['unique keys'])) {
@@ -1331,14 +1327,8 @@
               $real_columns[] = $table_mapping->getFieldColumnName($storage_definition, $column_name);
             }
           }
+          $this->database->schema()->addIndex($table, $real_name, $real_columns, $actual_schema[$table]);
+          $this->database->schema()->addIndex($revision_table, $real_name, $real_columns, $actual_schema[$revision_table]);
-          // Check if the index exists because it might already have been
-          // created as part of the earlier entity type update event.
-          if (!$this->database->schema()->indexExists($table, $real_name)) {
-            $this->database->schema()->addIndex($table, $real_name, $real_columns, $actual_schema[$table]);
-          }
-          if (!$this->database->schema()->indexExists($revision_table, $real_name)) {
-            $this->database->schema()->addIndex($revision_table, $real_name, $real_columns, $actual_schema[$revision_table]);
-          }
         }
       }
       $this->saveFieldSchemaData($storage_definition, $this->getDedicatedTableSchema($storage_definition));
@@ -1415,11 +1405,7 @@
             // Create new indexes and unique keys.
             if (!empty($schema[$table_name]['indexes'])) {
               foreach ($schema[$table_name]['indexes'] as $name => $specifier) {
+                $schema_handler->addIndex($table_name, $name, $specifier, $schema[$table_name]);
-                // Check if the index exists because it might already have been
-                // created as part of the earlier entity type update event.
-                if (!$schema_handler->indexExists($table_name, $name)) {
-                  $schema_handler->addIndex($table_name, $name, $specifier, $schema[$table_name]);
-                }
               }
             }
             if (!empty($schema[$table_name]['unique keys'])) {