Error in log on issue update/create

[kemaMartinsson]

I get the following error in redmine log after creating/updating an issue:
cannot connect to
uninitialized constant RedmineMsteams::TeamsMessage::HTTPClient

HTTPCient have been installed with both bundle install and gem install "httpclient" and verified that it's installed, redmine restarted.
Redmine verision 3.4.1

Testing the webhook with a simple Hello World works in MS Teams.
What am I missing? Ruby is not my cup of tea.

/Kenneth