Qual o erro que está dando no menu quando aparece Cannot resolve method inflate(int, Android.view.Menu)?

Estou tendo problemas com o menu. Fica aparecendo o erro "Cannot resolve method inflate(int, Android.view.Menu).

No messages gradle build aparece: Error:(35, 17) error: cannot find symbol method inflate(int,Menu).

Alguém sabe o problema que deu?

Segue o código abaixo até o momento.

package com.example.sugoi.agenda;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;


public class FormularioActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_formulario);

        Button botaoSalvar = (Button) findViewById(R.id.formulario_salvar);
        botaoSalvar.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(FormularioActivity.this, "Botão clicado!", Toast.LENGTH_LONG).show();
                finish();
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        Menu inflater = (Menu) getMenuInflater();

        inflater.inflate( R.menu.menu_formulario, menu);

        return super.onCreateOptionsMenu(menu);
    }
}