One of my remotes is S3 (named s3). I used to be able to run

$ git annex sync s3 --content

But now I'm getting the following error:

commit  
On branch master
nothing to commit, working directory clean
ok
git-annex: there is no available git remote named "s3"

My .git/config file contains following lines which I would assume mean that the remote is there:

[remote "s3"]
        annex-s3 = true
        annex-uuid = bd9af194-b736-4114-a689-9a8bf212fb18
        fetch = 
        annex-sync = false

As far as I can tell only change I did was to install newer version of git-annex, currently I have:

git-annex version: 6.20160418
build flags: Assistant Webapp Pairing Testsuite WebDAV FsEvents XMPP ConcurrentOutput TorrentParser MagicMime Feeds Quvi
key/value backends: SHA256E SHA256 SHA512E SHA512 SHA224E SHA224 SHA384E SHA384 SHA3_256E SHA3_256 SHA3_512E SHA3_512 SHA3_224E SHA3_224 SHA3_384E SHA3_384 SKEIN256E SKEIN256 SKEIN512E SKEIN512 SHA1E SHA1 MD5E MD5 WORM URL
remote types: git gcrypt bup directory rsync web bittorrent webdav tahoe glacier ddar hook external
local repository version: 6
supported repository versions: 5 6
upgrade supported from repository versions: 0 1 2 4 5

How do I recover access to that remote?