Search code examples
iosios9afnetworkingalamofire

NSURLErrorDomain Code=-1004 for few seconds after app start up

I'm getting "NSURLErrorDomain Code=-1004" error with Alamofire API calls, but only for few seconds after app started (or took a rest for few minutes while the app's opened and make a call after that)

If I try to make the same call after few seconds, everything works fine. I searched all the Stack Overflow questions and checked all the possible causes below:

  1. No problem with Internet connection
  2. "App Transport Security Settings" are correct and server's using https (I also tried "NSAllowsArbitraryLoads=true" but that didn't help)
  3. APIs working fine

My gut feeling is that getting the network settings takes few seconds and when I make an API call before that's done, it just fails immediately. OR.. I'm using a Websocket in background that could be related?

FAILURE: Error Domain=NSURLErrorDomain Code=-1004 "Could not connect to the server." UserInfo={NSUnderlyingError=0x137d39380 {Error Domain=kCFErrorDomainCFNetwork Code=-1004 "(null)" UserInfo={NSErrorPeerAddressKey={length = 16, capacity = 16, bytes = 0x100201bb341a9f540000000000000000}, _kCFStreamErrorCodeKey=-2200, _kCFStreamErrorDomainKey=4}}, NSErrorFailingURLStringKey=[FILTERED], NSErrorFailingURLKey=[FILTERED], _kCFStreamErrorDomainKey=4, _kCFStreamErrorCodeKey=-2200, NSLocalizedDescription=Could not connect to the server.}

Any suggestions?

UPDATED

Found that app makes 4 requests on launch, and 1 or 2 of them randomly fails, and I checked Nginx access and error log and there's no log for the failed calls at all.

Solution

  • We have the same issue here with Nginx 1.10.0 (and 1.9.15), iOS 9.3.1 using HTTP/2 with TLS 1.2.

    The issue goes away with HTTP/1.1 and it's also working with HTTP/2 in Nginx version up to 1.9.14.