Thanks for this article! It helped my upgrade from Mongodb 3.2 to 3.4.17 on my Ubuntu 16.04 DigitalOcean instance.

FYI, here’s what I had to run to completely upgrade my mongodb service:

• $ apt-get install mongodb-org=3.4.17
• $ mongod -v => still 3.2...

$ dpkg -l | grep mongo
ii  mongodb-org                       3.4.17                                     amd64        MongoDB open source document-oriented database system (metapackage)
ii  mongodb-org-mongos                3.2.19                                     amd64        MongoDB sharded cluster query router
ii  mongodb-org-server                3.2.19                                     amd64        MongoDB database server
ii  mongodb-org-shell                 3.2.19                                     amd64        MongoDB shell client
ii  mongodb-org-tools                 3.2.19                                     amd64        MongoDB tools
$ sudo apt-get install mongodb-org-tools=3.4.17

$ sudo apt-get install mongodb-org-shell=3.4.17

$ sudo apt-get install mongodb-org-server=3.4.17

$ sudo apt-get install mongodb-org-mongos=3.4.17

$ dpkg -l | grep mongo
ii  mongodb-org                       3.4.17                                     amd64        MongoDB open source document-oriented database system (metapackage)
ii  mongodb-org-mongos                3.4.17                                     amd64        MongoDB sharded cluster query router
ii  mongodb-org-server                3.4.17                                     amd64        MongoDB database server
ii  mongodb-org-shell                 3.4.17                                     amd64        MongoDB shell client
ii  mongodb-org-tools                 3.4.17                                     amd64        MongoDB tools

$ mongod -v
2018-09-15T12:17:05.803+0000 I CONTROL  [initandlisten] db version v3.4.17

$ sudo service mongodb restart

More info: https://github.com/openwhyd/openwhyd/issues/162#issuecomment-421559639