react componentWillUnmount 清除定时器 ajax请求 离开页面后还是会报内存泄漏的错误

Question

跳转页面后
在componentWillUnmount中,this.setState = ()=>false; 停止了异步 也清除了计时器 还是会报错

报错内容
Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method.
无法在未挂载的组件上执行React状态更新。这是一个无操作，但它表明应用程序中存在内存泄漏。要修复这个问题，请取消componentWillUnmount方法中的所有订阅和异步任务。

求助

export default class CommonTimer extends Component {

    state = {
        content: '',
        txts: '',
        passCurrentTime: 0,
        newCurrentTime: 0,
        flag: 1
    }

    countdowm = (timestamp) => {
        this.timer = setInterval(() => {
            this.setState({ passCurrentTime: this.state.passCurrentTime + 1000 })
            let DayTime = timestamp - this.state.passCurrentTime;
            console.log('1')
            if (DayTime > 1000) {
                var Hours = 60 * 60 * 1000,
                    Minutes = 60 * 1000,
                    Seconds = 1000;
                var hour = addZero(Math.floor(DayTime / Hours)),
                    minute = addZero(Math.floor((DayTime % Hours) / Minutes)),
                    second = addZero(Math.floor(((DayTime % Hours) % Minutes) / Seconds));
                this.setState({
                      txts: '距活动结束：',
                      content: hour + '小时' + minute + '分' + second + '秒'})
                } 

            function addZero(num) {
                return num < 10 ? "0" + num : "" + num;
            }
        }, 1000);
    }

    aaa = ()=>{
        this.props.history.push('buyercenter/coupon')
    }

    componentDidMount() {
        this.setState({ passCurrentTime: this.props.currentTime })
        if (this.props.currentTime < this.props.startTime) {
            this.countdowm(this.props.startTime);
        } else {
            this.setState({
                txts: '距活动结束：',
                content: '00小时00分00秒'
            })
        }
    }

    
    componentWillUnmount(){
        clearInterval(this.timer);
        this.setState = ()=>false;
    }

    render() {
        return (
            <div className={s.goods_item_time}>
            <span onClick={this.aaa}> 123123 </span>
                <span>{this.state.txts}</span>
                <span>{this.state.content}</span>
            </div>
        )
    }
}