I get this error message
Not Found: the requested item no longer exists.
on pages where wix-users-backend is called. Having as a result those pages stopped working. And in my router pages it results into an HTTP 500 error.
not just you. lost connection to my data a couple of time. logged out and turned on a movie.
Please put a ticket into Wix Support so that they can pass on the details to the relevant department as the Wix Admins/Mods for this Corvid Forum might not see this until Sunday at the earliest, thank you.
https://support.wix.com/en/about-wix/contacting-wix-customer-care
It might be routine maintenance or it could be an issue that Wix are already looking into and hopefully provide a fix soon. 
Have a look at this similar post here.
wixUsersBackend.currentUser.getRoles() error
Are you also trying to do something that is only viable through the frontend and not the backend?
@givemeawhisky Thank you for pointing that out. My god, I need those functions because its my authorisation module on the backend that needs those. I use those functions in my router logic, so there is not even a way to have a workaround. I don’t understand this even can happen without letting users knowing this through deprication… Will launch a support ticket too.
It seems its fixed… by Wix