uni-app下载文件异常，下载中途报错 unexpected EOF!

下载的代码如下，感觉没什么问题啊！

download() {  
                console.log("download click!");  
                var url= 'https://img-cdn-aliyun.dcloud.net.cn/guide/uniapp/%E7%AC%AC1%E8%AE%B2%EF%BC%88uni-app%E4%BA%A7%E5%93%81%E4%BB%8B%E7%BB%8D%EF%BC%89-%20DCloud%E5%AE%98%E6%96%B9%E8%A7%86%E9%A2%91%E6%95%99%E7%A8%8B@20181126.mp4';   
                const downloadTask = uni.downloadFile({  
                    url: url,   
                    success: (res) => {  
                        if (res.statusCode === 200) {  
                            console.log(JSON.stringify(res));  
                            console.log('下载成功');  
                        }  
                    },  
                    fail: (res) => {  
                        console.log(JSON.stringify(res));  
                    }  
                });  

                downloadTask.onProgressUpdate((res) => {  
                    console.log('下载进度' + res.progress + '%');  
                    console.log('已经下载的数据长度' + res.totalBytesWritten / 1024 + 'Kb');  
                    console.log('预期需要下载的数据总长度' + res.totalBytesExpectedToWrite / 1024 + 'Kb');  
                    // 测试条件，取消下载任务。  
                });  
            }

报错信息：

15:27:21.061 已经下载的数据长度912.8427734375Kb at pages/template/curriculum/play.vue:444
15:27:21.082 预期需要下载的数据总长度22379.5888671875Kb at pages/template/curriculum/play.vue:445
15:27:21.103 下载进度4% at pages/template/curriculum/play.vue:443
15:27:21.127 已经下载的数据长度914.2099609375Kb at pages/template/curriculum/play.vue:444
15:27:21.148 预期需要下载的数据总长度22379.5888671875Kb at pages/template/curriculum/play.vue:445
15:27:21.169 下载进度4% at pages/template/curriculum/play.vue:443
15:27:21.191 已经下载的数据长度915.5771484375Kb at pages/template/curriculum/play.vue:444
15:27:21.211 预期需要下载的数据总长度22379.5888671875Kb at pages/template/curriculum/play.vue:445
15:27:21.232 下载进度4% at pages/template/curriculum/play.vue:443
15:27:21.252 已经下载的数据长度916.9443359375Kb at pages/template/curriculum/play.vue:444
15:27:21.272 预期需要下载的数据总长度22379.5888671875Kb at pages/template/curriculum/play.vue:445
15:27:21.293 unexpected EOF!

各位大神帮忙看看是什么问题啊！