Update (Monday, 14 August 2017)

It’s official, a fix is rolling out to production.

Update (Sunday, 13 August 2017)

The service seems to go back online in stages according to various posts. It’s funny that the support teams are not aware that there is a single error message. One for the Health apps and one for the Health dashboard:

App (sorry, in French):

Echec de l’authentification

Nous n’avons pas réussi à vous connecter. Réessayer.

Dashboard:

An error occurred!

Something went wrong. Please wait a moment and try again.

Sometimes signing out and signing back in can help fix the issue.

Support team response on the Community Help Desk:

Microsoft Band App on Windows 10 Mobile stopped Syncing data..

…
Please try to login to your Microsoft Health App and dashboard today.
If you are still unable to sync your device due to failed log in issue, kindly please reply back to this email with the error message you are getting.
…

And the winner is … the Band App that probably displays the real error message.

End of Update.

The MS Health Platform that powers the MS Health Apps and respective bands is down for several days at the time I’m writing these lines.

This is the cloud, it happens.

Your phone and web apps should be prepared to a cloud powered backend issue. Please do not display a useless error message to your users like ‘A network error occurred, please try again later’.

Also, talk to your customers and do not send useless FAQ. This is a new problem. Fix it and fix your error messages in your apps.

Always improve your bridge.