panic: Session already closed

goroutine 488 [running]:
dev.tightvideo.com/prebilling/vendor/gopkg.in/mgo%2ev2.(*Session).cluster(...)
	/home/fe/gopath/src/dev.tightvideo.com/prebilling/vendor/gopkg.in/mgo.v2/session.go:1624
dev.tightvideo.com/prebilling/vendor/gopkg.in/mgo%2ev2.copySession(0xc0004449c0, 0xc0002dd501, 0xdac780)
	/home/fe/gopath/src/dev.tightvideo.com/prebilling/vendor/gopkg.in/mgo.v2/session.go:540 +0x372
dev.tightvideo.com/prebilling/vendor/gopkg.in/mgo%2ev2.(*Session).Copy(0xc0004449c0, 0xcc54c0)
	/home/fe/gopath/src/dev.tightvideo.com/prebilling/vendor/gopkg.in/mgo.v2/session.go:1590 +0x40
main.(*Updater).update(0xc0003521c0, 0xf60660, 0xc00026e580, 0xc00016cb00, 0xdc4d6d, 0x6, 0xc0005a5180)
	/home/fe/gopath/src/dev.tightvideo.com/prebilling/cmd/ivi/updater.go:160 +0xb6
created by main.(*Updater).Run.func1
	/home/fe/gopath/src/dev.tightvideo.com/prebilling/cmd/ivi/updater.go:302 +0x202
time="2020-03-30T15:46:21+03:00" level=debug msg="Logger level is debug. Change it in production"
time="2020-03-30T15:46:21+03:00" level=info msg="start monitoring server on :14113"