when we double click any button this is error occurring, where is the error

This is the error occurring :-

NullReferenceException: (null)
UnityEngine.MonoBehaviour.StopCoroutine (UnityEngine.Coroutine routine) (at C:/buildslave/unity/build/artifacts/generated/common/runtime/MonoBehaviourBindings.gen.cs:99)

This is the Code :-

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Test : MonoBehaviour {

public GameObject Testobject;

public GameObject Main_Menu;
public Material[] TestShaders;
public Texture[] TestTextures;
public Texture[] TestPatterns;
public Color[] TestColors;

int m;

//To Change Menus 
public void Change_Menus(int x)
	for (int y = 1; y < Main_Menu.transform.childCount; y++) 
		Main_Menu.transform.GetChild(y).gameObject.SetActive (false);
	Main_Menu.transform.GetChild (x).gameObject.SetActive (true);

	x = m;
//To Function Shader 
public void Function_Shader_Menus(int x)
	Testobject.GetComponent<Renderer> ().material = TestShaders[x];
//To Function Texture
public void Function_Texture_Menus(int x)
	Testobject.GetComponent<Renderer> ().material.mainTexture = TestTextures[x];
//To Function Pattern
public void Function_Pattern_Menus(int x)
	Testobject.GetComponent<Renderer> ().material.mainTexture = TestPatterns[x];
//To Function Pattern Color 
public void Function_Pattern_Color_Menus(int x)
	Testobject.GetComponent<Renderer> ().material.color = TestColors[x];


May not be in the code you have attached. It seems like a Coroutine is broken, but you are not using Coroutines in this snippet. Try not to SetActive(false) in your loop, Debug.Log you x and y values and compare with what you have initiated them with. This is my best advice based on the provided information.

Thanks Bro for the quick response.
I figured out though using VRTK, It was a code error in VRTK UI canvas.