I opened the dashboard several times in a separate chrome tabs to check the work status of my colleagues.
Then I left it open. Several of them threw the same error, sooner or later.

I don't know... https://packager.fedorainfracloud.org/mmuzila seems to work fine for me :/ Tried multiple times in last 15 minutes. Is it still broken for you?

I'll try to reproduce again.

If I won't reply in 3 days, feel free to close the ticket.

I opened a total of 7 tabs with for different packagers, let's wait till the error re-appears.

The error you've mentioned basically means that the frontend can't reach backend. There could've been some minor hiccup, but I don't see anything obvious in logs. We had some minor downtime yesterday as the server was overloaded (probably due to testday happening and syncing large amount of Packager Dashboard data at the same time).

This issue has been migrated to Fedora Forge:
https://forge.fedoraproject.org/apps/packager_dashboard/issues/51

Please continue any further discussion there.