ESP8266mDNS Library error in Arduino

Hello
I'm trying to compile a program but it doesn't work because of these errors:

In file included from C:\Users\xxx\Documents\Arduino\libraries\ESP8266mDNS\src/ESP8266mDNS.h:46:0,

                 from C:\Users\xxx\Downloads\other\ESP32-8266-File-Upload-master\ESP_File_Download_Upload\ESP_File_Download_Upload.ino:26:

C:\Users\xxx\Documents\Arduino\libraries\ESP8266mDNS\src/LEAmDNS.h:910:9: error: 'oneShotMs' in namespace 'esp8266::polledTimeout' does not name a type

         esp8266::polledTimeout::oneShotMs m_Timeout;      // Used for probes and announcements

         ^

C:\Users\xxx\Documents\Arduino\libraries\ESP8266mDNS\src/LEAmDNS.h:978:17: error: 'oneShotMs' in namespace 'esp8266::polledTimeout' does not name a type

                 esp8266::polledTimeout::oneShotMs m_TTLTimeout;

                 ^

C:\Users\xxx\Documents\Arduino\libraries\ESP8266mDNS\src/LEAmDNS.h:1081:9: error: 'oneShotMs' in namespace 'esp8266::polledTimeout' does not name a type

         esp8266::polledTimeout::oneShotMs m_ResendTimeout;

         ^

exit status 1
Fehler beim Kompilieren für das Board NodeMCU 1.0 (ESP-12E Module).

I've tried to delete all libraries in my documents and in my local files and started from the beginning and I attempted to delete these functions because I don't need them in my Code. But it didn't worked out.
This is the Code which I'm using:

the program includes these libraries which are all installed from https://github.com/esp8266/Arduino:

#include <ESP8266WiFi.h>       // Built-in
#include <ESP8266WiFiMulti.h>  // Built-in
#include <ESP8266WebServer.h>  // Built-in
#include <ESP8266mDNS.h>
#include <SD.h>
#include <SPI.h>

does somebody knows how to fix this error?

Check in your Boards Manager which version of the ESP8266 core you have installed. In my version 2.5.1 the EXP8266mDNS library comes pre-installed by the core.

That worked!
Thanks alot I had the version 2.5.0 and updated it.