在WiFi上传时出现NSURLSession错误：NSURLErrorDomain Code = -999

I built an app, more than an year ago, that provides photo sharing and video sharing for its users. It ran without any problems until a couple of weeks ago where I introduced a new feature: the possibility of marking a video to be uploaded only when WiFi is available: the video is set to use an NSURLSession with a NSURLSessionConfiguration where allowsCellular is set to NO.I built an app, more than an year ago, that pro