iOS "protocol error"


I’m running into some problems with my wife’s iPhone. ALL other devices (Windows, Linux, Android, web) work perfectly, only the dumb iPhone does not want to connect to the server. Even more interesting:

  • Caldav & Carddav work even on the iPhone.
  • Safari & Firefox on the phone will not connect to the sever either, no error message whatsoever.
  • When trying to connect via the nextcloud app, I only receive an “protocol error” without more detail.
  • rates the server as A+.
  • When I try to connect, the iOS app gives a protocol error. After entering username and password, the app gives an error (“It is not possible to connect to the server at this time (null)”), but nextcloud logging shows an successful login for her username (which obviously did not work).

Do you have any ideas what might be causing this problem?

Best regards,


Nextcloud version: 13.0.5, but I’m having this problem since a few months
Operating system and version: Raspbian 9 (stretch)
Apache or nginx version: nginx 1.10.3
PHP version: 7.0

I asked a colleague with an iPhone to open the website in Safari, he also could not connect.

SSL is provided via a LetsEncrypt certificate. Do I have to provide a certain protocol in order to allow iOS devices to connect?

Does anyone have a nextcloud instance running, with SSL, which works with iOS devices?


Maybe it also helps to provide info which apps/sync are working in iOS.

  • Caldav/Carddav sync for calendar and contacts, configuration in the iOS settings.

Not working:

  • Opening URL in Safari or Firefox on (two) iPhones (all other platforms can open the URL in a browser).
  • Connecting the nextcloud app (error message regarding protocol).
  • Connecting the nextcloud Talk app (no error message, just loading forever). (Works on my Android phone like a charm.)

APPLE BEURK… always something wrong this apple products …
Ok, rant finish,

  • Safari doesnt need any particular ssl protocol, or order in your server conf.

sending you a private link for testing…


It’s working again, I reimplemented the SSL encryption with some (in my opinion) minor differences. Basically I used the values and configuration given here (It’s in German but describes more or less completely what I wanted).

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