I can't update variables with setState inside axios

I am developing a query to an api using axios with react . The responses arrive correctly but I am not being able to update the status of a variable, which shows errors from the server or correct login

In the console, it tells me that the this operator is undefined.

The code of my function is the following:

consumirApiLogin() {
    const payload={
        "_username":this.state.username,
        "_password":this.state.password,
    }
    axios.post(API_LOGIN, payload)
        .then(function (response) {
            this.setState({errorApi: response.data})
        })
        .catch(function (e) {
            console.log(e);
            let error = '';
            if(e.response)
            {
                let error = e.response.message;
            }
            this.setState({errorApi: error})
        });
}

My constructor is the following:

 constructor(props){
    super(props);

    this.state = ({
        username:'',
        password:'',
        errors: {},
        errorApi: ''
    })

    this.cambioUsername = this.cambioUsername.bind(this);
    this.cambioPassword = this.cambioPassword.bind(this);
    this.handleSubmit   = this.handleSubmit.bind(this); 
    this.consumirApiLogin = this.consumirApiLogin.bind(this);
    this.validarFormulario = this.validarFormulario.bind(this);
}

Any help is welcome! Greetings!