HarmonyOS 鸿蒙Next 下载文件到沙盒时报错 13400001 : file operation error

let context = getContext(this) as common.UIAbilityContext;

this.downloadFile(url, <span class="hljs-subst">${context.filesDir}</span>/123.zip) 
downloadFile(url: string, saveFile: string): Promise<void> {
const promise = request.downloadFile(context, { url: url, filePath: saveFile })
const newPromise = new Promise<void>((resolve: Function, reject: Function) => {
promise.then((downloadTask: request.DownloadTask) => {
downloadTask.on(‘complete’, () => {
resolve()
})
downloadTask.on(‘fail’, (err: number) => {
console.error(‘err:’ + err)
reject(new NetError(NetErrType.LogicErr, err, ‘downloadTask error’))
})
downloadTask.on(‘progress’, (receivedSize: number, total: number) => {
console.error(progress:<span class="hljs-subst">${receivedSize}</span>,total:<span class="hljs-subst">${total}</span>)
})
}).catch((e: Error) => {
console.error(‘downloadFile err:’, e.message)
reject(e)
})
})
return newPromise
}