On an installation of Sitecore 8.2 update 4, the mongo connection appears to work fine. After upgrading to Sitecore 8.2 update 6 mongo is stating that the connection string is not valid.
The connection string 'mongodb://username:password@servername.fleet.mongolab.com:port138192/databasename?replicaSet=rs-servername;ssl=true' is not valid.
What may have happened to cause this and how can I get it working?