I am busy updating my sites today, and had problems with the Available Updates "Failed to get available updates" or something similar at about 1055 UTC.
When I went to the backdrop CMS site I got a page with this error:
Backdrop CMS Error SQLSTATE[HY000] [1040] Too many connections
Looks like Backdrop is getting very popular!!!!
Fortunately this has now cleared.
There have been scattered reports of this problem in our chat channel and our volunteer server admin is aware and will look into it ASAP.
As far as I can tell, things are working sporadically. So, until things get fixed, please be patient and try back soon.