Scenario (i.e., this was my situation)

  • You are able to log in normally to windows 10 (with your own account, set as standard or as administrator, and with the usually hidden SuperAdministrator account)
  • Safe mode and safe mode with networking are working
  • Safe mode with command prompt shows no administrator accounts and this message: You need to sign in as an administrator to continue, but there aren't any administrator accounts on this PC..
    Hence you aren't able to use the safe mode with command prompt.
  • Your C:\Recovery\WindowsRE folder contains the winre.wim (windows image) file necessary to get the windows advanced startup settings

Solution

Re-register the winre image with:
reagentc /disable
reagentc /enable
Additional information:

reagentc /info (ran from an elevated command prompt) shows:
Read More:
Partition4 is my C:, i.e. my system partition.

bcdedit (ran from an elevated command prompt) shows recoverysequence {4a081ca8-71be-11e6-80cd-eca86b8ec766} (under windows boot loader):
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I got this problem after I've accidentally removed all administrator accounts from netplwiz = control userpasswords2 (user accounts advanced menu?) some weeks/months ago.
I consider that a BUG in windows: we shouldn't be able to remove all administrator accounts!!!
I can't remember how I solved that problem; that's why I'm posting this: to remember how I did it, in the hope it could be useful for someone else.