File download failed

Failed to send -[BADownloaderExtensionProxy backgroundDownload:finishedWithSandboxToken:completionHandler:]_block_invoke for: com.xuhuiTest.photos error: Error Domain=NSCocoaErrorDomain Code=4097 "connection to service with pid 2085 named com.xuhuiTest.photos.BackgroundDownloadExt" UserInfo={NSDebugDescription=connection to service with pid 2085 named com.xuhuiTest.photos.BackgroundDownloadExt}

Client is missing signing identifier, client must be signed with an identifier to use BackgroundAssets. (null)