MongoDb 3.4 will reach end of life support in January 2020 (as stated here). Currently Sitecore XP 8.2 is compatible with MongoDb 3.4. Customers using Sitecore XP 8.2 must upgrade to MongoDb version 3.6.
The following upgrade process has been tested with MongoDb 3.6.6.
Customers using Sitecore XP versions earlier than 8.2.7 must upgrade to Sitecore XP 8.2.7.
Mongo driver update procedure:
Please contact Sitecore Support in case of any issues.