NSURLErrorDomain Code=-2000 "can’t load from network" - ios

Question

My app started accidentally with an error that I never had before and I can't find any solution around the net. I think it has nothing to do with my code but if it helps, here it is:
class InterfaceController: WKInterfaceController {
#IBOutlet var tableView: WKInterfaceTable!
final let url = URL(string: "http://...")
private var tasks = [Task]()
override func awake(withContext context: Any?) {
super.awake(withContext: context)
downloadJson()
}
func downloadJson() {
guard let downloadURL = url else { return }
URLSession.shared.dataTask(with: downloadURL) { data, urlResponse, error in
guard let data = data, error == nil, urlResponse != nil else {
print("something is wrong")
return
}
do
{
let decoder = JSONDecoder()
let downloadedTasks = try decoder.decode(Tasks.self, from: data)
self.tasks = downloadedTasks.tasks
print(self.tasks)
} catch {
print("somehting went wrong after downloading")
}
}.resume()
}
}
The error message I'm getting in the console is:
2018-11-07 21:34:15.538369+0100 BJwatch WatchKit Extension[1884:84116] Task <82BE34C9-CCAB-4076-8012-CC9FF61AE556>.<1> load failed with error Error Domain=NSURLErrorDomain Code=-2000 "can’t load from network" UserInfo={NSLocalizedDescription=can’t load from network, _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask <82BE34C9-CCAB-4076-8012-CC9FF61AE556>.<1>, _NSURLErrorRelatedURLSessionTaskErrorKey=(
"LocalDataTask <82BE34C9-CCAB-4076-8012-CC9FF61AE556>.<1>"
), NSErrorFailingURLStringKey=http://..., _kCFNetworkErrorConditionalRequestKey=<CFMutableURLRequest 0x7c09bc70 [0x34f528c]> {url = http://..., cs = 0x0}, _kCFNetworkErrorCachedResponseKey=<CFCachedURLResponse 0x7afc2840 [0x34f528c]>, NSUnderlyingError=0x7c1eb930 {Error Domain=kCFErrorDomainCFNetwork Code=-2000 "(null)" UserInfo={_kCFNetworkErrorCachedResponseKey=<CFCachedURLResponse 0x7afc2840 [0x34f528c]>, _kCFNetworkErrorConditionalRequestKey=<CFMutableURLRequest 0x7c09bc70 [0x34f528c]> {url = http://..., cs = 0x0}}}, NSErrorFailingURLKey=http://...} [-2000]
[BJwatch_WatchKit_Extension.Task, BJwatch_WatchKit_Extension.Task, BJwatch_WatchKit_Extension.Task, BJwatch_WatchKit_Extension.Task]
The URL is not "http://..." in the real app. It is a URL that gives a JSON array and it is working.

Answer 1

NSURLErrorCannotLoadFromNetwork
This error is sent when the task needs to load from the network, but is blocked from doing so by the “load only from cache” directive.
The default policy is NSURLRequest.CachePolicy.useProtocolCachePolicy
useProtocolCachePolicy: Use the caching logic defined in the protocol implementation, if any, for a particular URL load request.
Important: If you are making HTTP or HTTPS byte-range requests, always use the NSURLRequest.CachePolicy.reloadIgnoringLocalCacheData policy instead.
var request = URLRequest(url: URL(string:"http://...")!)
request.cachePolicy = URLRequest.CachePolicy.reloadIgnoringLocalCacheData
URLSession.shared.dataTask(with: request) {...

Answer 2

Correct answer to fix this is to change URLSessionConfiguration. If anyone still want to use .useProtocolCachePolicy policy, use background configuration.
let configuration = URLSessionConfiguration.background(withIdentifier: "xxx.xxx.xxxxx")
let session = URLSession(configuration: configuration)
Below is what I get from Apple's support.
Watch apps tend to be suspended very quickly so we recommend that developers use a background url session to ensure their api calls are still performed should an event such as backgrounding or suspension occur.