diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index e06a581094..f5753fe426 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -164,7 +164,7 @@ module ActiveRecord
   end
 
   class EnvironmentMismatchError < ActiveRecordError
-    def initialize(current: , stored: )
+    def initialize(current: nil, stored: nil)
       msg =  "You are attempting to modify a database that was last run in #{ stored } environment.\n"
       msg << "You are running in #{ current } environment."
       msg << "if you are sure you want to continue, run the same command with the environment variable\n"
@@ -1238,7 +1238,12 @@ module ActiveRecord
     end
 
     def self.last_stored_environment
-      ActiveRecord::InternalMetadata[:environment]
+      return nil if current_version == 0
+      raise NoEnvironmentInSchemaError unless ActiveRecord::InternalMetadata.table_exists?
+
+      environment = ActiveRecord::InternalMetadata[:environment]
+      raise NoEnvironmentInSchemaError unless environment
+      environment
     end
 
     def self.current_environment
@@ -1246,11 +1251,7 @@ module ActiveRecord
     end
 
     def self.protected_environment?
-      return false if current_version == 0
-      raise NoEnvironmentInSchemaError unless ActiveRecord::InternalMetadata.table_exists?
-
-      raise NoEnvironmentInSchemaError unless last_stored_environment
-      ActiveRecord::Base.protected_environments.include?(last_stored_environment)
+      ActiveRecord::Base.protected_environments.include?(last_stored_environment) if last_stored_environment
     end
 
     def up?
diff --git a/activerecord/lib/active_record/tasks/database_tasks.rb b/activerecord/lib/active_record/tasks/database_tasks.rb
index d51f38c93f..7b8f27699a 100644
--- a/activerecord/lib/active_record/tasks/database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/database_tasks.rb
@@ -51,8 +51,8 @@ module ActiveRecord
             raise ActiveRecord::ProtectedEnvironmentError.new(stored)
           end
 
-          if current != stored
-            raise EnvironmentMismatchError.new(current: current, stored: stored)
+          if stored && stored != current
+            raise ActiveRecord::EnvironmentMismatchError.new(current: current, stored: stored)
           end
         end
       rescue ActiveRecord::NoDatabaseError
diff --git a/activerecord/test/cases/schema_dumper_test.rb b/activerecord/test/cases/schema_dumper_test.rb
index 97c3d664ba..2006f40b25 100644
--- a/activerecord/test/cases/schema_dumper_test.rb
+++ b/activerecord/test/cases/schema_dumper_test.rb
@@ -38,7 +38,7 @@ class SchemaDumperTest < ActiveRecord::TestCase
     assert_match %r{create_table "accounts"}, output
     assert_match %r{create_table "authors"}, output
     assert_no_match %r{create_table "schema_migrations"}, output
-    assert_no_match %r{create_table "internal_metadatas"}, output
+    assert_no_match %r{create_table "active_record_internal_metadatas"}, output
   end
 
   def test_schema_dump_uses_force_cascade_on_create_table
@@ -159,7 +159,7 @@ class SchemaDumperTest < ActiveRecord::TestCase
     assert_no_match %r{create_table "accounts"}, output
     assert_match %r{create_table "authors"}, output
     assert_no_match %r{create_table "schema_migrations"}, output
-    assert_no_match %r{create_table "internal_metadatas"}, output
+    assert_no_match %r{create_table "active_record_internal_metadatas"}, output
   end
 
   def test_schema_dump_with_regexp_ignored_table
@@ -167,7 +167,7 @@ class SchemaDumperTest < ActiveRecord::TestCase
     assert_no_match %r{create_table "accounts"}, output
     assert_match %r{create_table "authors"}, output
     assert_no_match %r{create_table "schema_migrations"}, output
-    assert_no_match %r{create_table "internal_metadatas"}, output
+    assert_no_match %r{create_table "active_record_internal_metadatas"}, output
   end
 
   def test_schema_dumps_index_columns_in_right_order
@@ -345,7 +345,7 @@ class SchemaDumperTest < ActiveRecord::TestCase
     assert_no_match %r{create_table "foo_.+_bar"}, output
     assert_no_match %r{add_index "foo_.+_bar"}, output
     assert_no_match %r{create_table "schema_migrations"}, output
-    assert_no_match %r{create_table "internal_metadatas"}, output
+    assert_no_match %r{create_table "active_record_internal_metadatas"}, output
 
     if ActiveRecord::Base.connection.supports_foreign_keys?
       assert_no_match %r{add_foreign_key "foo_.+_bar"}, output
diff --git a/railties/test/application/bin_setup_test.rb b/railties/test/application/bin_setup_test.rb
index c96bbe4c70..d279f198f2 100644
--- a/railties/test/application/bin_setup_test.rb
+++ b/railties/test/application/bin_setup_test.rb
@@ -28,7 +28,7 @@ module ApplicationTests
         assert_not File.exist?("tmp/restart.txt")
         `bin/setup 2>&1`
         assert_equal 0, File.size("log/my.log")
-        assert_equal '["articles", "schema_migrations", "internal_metadatas"]', list_tables.call
+        assert_equal '["articles", "schema_migrations", "active_record_internal_metadatas"]', list_tables.call
         assert File.exist?("tmp/restart.txt")
       end
     end
diff --git a/railties/test/application/rake/dbs_test.rb b/railties/test/application/rake/dbs_test.rb
index 47ab65e57b..1304e73378 100644
--- a/railties/test/application/rake/dbs_test.rb
+++ b/railties/test/application/rake/dbs_test.rb
@@ -222,14 +222,14 @@ module ApplicationTests
 
           assert_equal '["posts"]', list_tables[]
           `bin/rake db:schema:load`
-          assert_equal '["posts", "comments", "schema_migrations", "internal_metadatas"]', list_tables[]
+          assert_equal '["posts", "comments", "schema_migrations", "active_record_internal_metadatas"]', list_tables[]
 
           app_file 'db/structure.sql', <<-SQL
             CREATE TABLE "users" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "name" varchar(255));
           SQL
 
           `bin/rake db:structure:load`
-          assert_equal '["posts", "comments", "schema_migrations", "internal_metadatas", "users"]', list_tables[]
+          assert_equal '["posts", "comments", "schema_migrations", "active_record_internal_metadatas", "users"]', list_tables[]
         end
       end