HTTP Error: 599 "" (https://premium.wpmudev.org/api/dashboard/v1/updates [599])

Got this in the roor error_log

[27-Sep-2016 14:13:25 UTC] [WPMUDEV API Error] 4.1.2 | HTTP Error: 599 "" (https://premium.wpmudev.org/api/dashboard/v1/updates [599])
[27-Sep-2016 14:13:27 UTC] [WPMUDEV API Error] 4.1.2 | HTTP Error: 599 "" (https://premium.wpmudev.org/api/dashboard/v1/updates [599])
[27-Sep-2016 14:13:28 UTC] [WPMUDEV API Error] 4.1.2 | HTTP Error: 599 "" (https://premium.wpmudev.org/api/dashboard/v1/updates [599])
[27-Sep-2016 21:37:55 UTC] [WPMUDEV API Error] 4.1.2 | HTTP Error: 599 "" (https://premium.wpmudev.org/api/dashboard/v1/updates [599])
[28-Sep-2016 10:01:14 UTC] [WPMUDEV API Error] 4.1.2 | HTTP Error: 599 "" (https://premium.wpmudev.org/api/dashboard/v1/updates [599])