End to End encryption error

Description

Hey folks,
we tried to enable the end to end encryption and ran into some Problems. Every time a user restarts the application a new key is generated.
If we enable the e2e in a chat we are not able to send messages. The error showing up says “cannot read property ‘slice’ of undefiend”, other users reported it says “cannot read property ‘a’ of undefiend”.

All communication is http because we access via vpn, maybe thats an important information.
Please tell me if you need additional information.

Server Setup Information

  • Version of Rocket.Chat Server: 3.7.1
  • Operating System: Linux, 4.15.0-123-generic
  • Deployment Method: Ubuntu, manual install
  • Node Version: v12.14.0
  • MongoDB Version: 4.0.21
  • Proxy: ngix
  • Firewalls involved: no