Looks like we're in the clear; we've isolated the issue, and folks should be able to connect again. If you're still having troubles, a clear of your app's cache should solve the problem. You can do so by heading to Help > Troubleshooting > Clear cache and restart. If you are using Slack in a web browser, please clear its cache. As always, please drop us a note at firstname.lastname@example.org if everything doesn't return to normal.
10:47 AM PST
We're still looking into the root cause of the connectivity issues; we apologize for any disruption to your workflow.
10:19 AM PST
Some folks are having troubles connecting to their workspace in various regions; we're currently investigating the cause. Thanks for your understanding.
9:51 AM PST