Can't send alerts via Direct Message to User with Slack Integration

I have an on-premise install of sentry and am trying to set up alerting via DM. I am able to set up alerts to channels, but when I try to set a user, for example ‘@firstname.lastname’ the follow error occurs:

The slack resource “firstname.lastname” does not exist or has not been granted access in the $WORKSPACENAME workspace.

It looks like you’re able to send DMs via the documentation:
https://docs.sentry.io/guides/alert-notifications/routing-alerts/

" The action enables routing alert notifications to selected Channels (using the # prefix) or Direct Messages (using the @ prefix) in your Slack Workspaces."

sentry version: Sentry 10.1.0.dev079b31fc

Heya,

Sorry about this. Our Slack integration had to go through some updates so

  1. Can you try upgrading to the latest Sentry (20.7.2 at this time)
  2. Can you follow this new guide to make sure you don’t miss anything: https://develop.sentry.dev/integrations/slack/

I upgraded to the latest version of on-premise and solved the issue. The install wasn’t as straight forward as running the install.sh though, it required pulling the latest version from github due to (what seems to be) a new nginx container, i documented and closed an issue here: