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:
- No problem with Internet connection
- "App Transport Security Settings" are correct and server's using https (I also tried "NSAllowsArbitraryLoads=true" but that didn't help)
- 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.
Answer
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.