We have recently renewed our MongoDB 3.4 signing key. If you try to install MongoDB 3.4 and you receive an expired key error, this may mean that you still have the old key imported on your system and you will need to update it.
The specific procedure varies on different systems. The below example is from Ubuntu 16.04 and uses apt package manager:
Check to see if you have the old key imported:
sudo apt-key list
pub 4096R/A15703C6 2016-01-11 [expires: 2020-01-05]
uid MongoDB 3.4 Release Signing Key <pack...@mongodb.com>
If you do, remove the old key:
sudo apt-key del A15703C6
OK
Then re-import the new, updated key:
wget -qO - https://www.mongodb.org/static/pgp/server-3.4.asc | sudo apt-key add -
You can find MongoDB 3.4 installation instructions for all supported platforms here:
https://docs.mongodb.com/v3.4/installation/
Kind regards,
Kelsey