Uncaught TypeError: $(...).dragster is not a function

Hi There,

I'm using Mattermost version 2.1. I see this error in the Platforms log:

[2016/04/07 11:21:06 UTC] [EROR] /api/v1/admin/log_client:client code=0 rid=YYYYYYYYYY uid=XXXXXXXXXX ip=172.16.0.212, 172.18.0.1 msg: Uncaught TypeError: $(...).dragster is not a function row: 13 col: 13135 stack: TypeError: $(...).dragster is not a function url: https://chat.taktsoft.com/static/js/bundle-2.1.0.min.js [details: ]

which causes the client (In this case: Chrome) to reload the site. This happens every time, the Clients user clicks to another channel in Mattermost. Any ideas how to Fix this?

Kind regards,
Michael