diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 13f7649e67..0e624ddb4d 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -39,6 +39,12 @@
 
     *Jenn Cooper*
 
+*   Do not use `RENAME INDEX` syntax for MariaDB 10.0.
+
+    Fixes #15931.
+
+    *Jeff Browning*
+
 *   Calling `#empty?` on a `has_many` association would use the value from the
     counter cache if one exists.
 
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index ccb957d2c8..e5417a9556 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -473,7 +473,7 @@ module ActiveRecord
       end
 
       def rename_index(table_name, old_name, new_name)
-        if (version[0] == 5 && version[1] >= 7) || version[0] >= 6
+        if supports_rename_index?
           execute "ALTER TABLE #{quote_table_name(table_name)} RENAME INDEX #{quote_table_name(old_name)} TO #{quote_table_name(new_name)}"
         else
           super
@@ -774,10 +774,22 @@ module ActiveRecord
 
       private
 
+      def version
+        @version ||= full_version.scan(/^(\d+)\.(\d+)\.(\d+)/).flatten.map { |v| v.to_i }
+      end
+
+      def mariadb?
+        full_version =~ /mariadb/i
+      end
+
       def supports_views?
         version[0] >= 5
       end
 
+      def supports_rename_index?
+        mariadb? ? false : (version[0] == 5 && version[1] >= 7) || version[0] >= 6
+      end
+
       def configure_connection
         variables = @config.fetch(:variables, {}).stringify_keys
 
diff --git a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
index 0a14cdfe89..39d52e6349 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
@@ -269,8 +269,8 @@ module ActiveRecord
         super
       end
 
-      def version
-        @version ||= @connection.info[:version].scan(/^(\d+)\.(\d+)\.(\d+)/).flatten.map { |v| v.to_i }
+      def full_version
+        @full_version ||= @connection.info[:version]
       end
 
       def set_field_encoding field_name
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index ad07a46e51..a03bc28744 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -470,9 +470,9 @@ module ActiveRecord
         rows
       end
 
-      # Returns the version of the connected MySQL server.
-      def version
-        @version ||= @connection.server_info.scan(/^(\d+)\.(\d+)\.(\d+)/).flatten.map { |v| v.to_i }
+      # Returns the full version of the connected MySQL server.
+      def full_version
+        @full_version ||= @connection.server_info
       end
 
       def set_field_encoding field_name