Jenkins Slack integration

Finally, the issue was a temporary bug. Our configuration was valid, and re-testing a few days later seems to work well.

We filled Team Subdomain and Integration Token inputs with information found in our Slack apps management page. In addition, we set the name of the Channel were Jenkins will push notifications:

We didn't set nothing in Slack Webhooks Settings:

Important: Remember to save your settings before clicking on "Test Connection" button.

Versions: Jenkins 2.46 / Slack Notification Plugin 2.2. Settings info found on https://github.com/jenkinsci/slack-plugin

I had the same issue and found out that I had to create an incoming webhook on the slack interface (https://slack.com/apps/A0F7XDUAZ-incoming-webhooks)
But still I cant get it working...

edit: I may have misinterpreted the installation instruction at https://github.com/jenkinsci/slack-plugin, anyway it's not up to date

leave "baseUrl" empty, and save before test via "TestConnection".