404 error when using webhook

Hello
when I am trying to start build by GET request - receive 404 error and json:
{“error”:“404 Not Found”}
Here is a request:
http://gitlab.server/api/v3/projects/4/ref/master/trigger/builds?token=d0b87...5e5a
the POST request with the same token and ref works great:
curl -X POST -F token=d0b87…5e5a -F ref=master http://gitlab.server/api/v3/projects/4/trigger/builds
returns
{“id”:4,“variables”:null}

uname -a
Linux gitlab 4.4.0-47-generic #68-Ubuntu SMP Wed Oct 26 19:39:52 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

/var/log/gitlab/nginx/gitlab_access.log:
“GET /api/v3/projects/4/ref/master/trigger/builds?token=d0b87…5e5a HTTP/1.1” 404 56 “-”

/var/log/gitlab/gitlab-rails/production.log:
Started GET “/api/v3/projects/4/ref/master/trigger/builds?token=d0b87…5e5a” for 111.111.111.111 at 2016-12-06 12:02:04 +0000

gitlab 8.14.3

Why 404?