Para resolver esse problema, digite os seguintes comandos em um prompt de comando elevado:

TAKEOWN /f %windir%\winsxs\temp\PendingRenames /a
icacls %windir%\winsxs\temp\PendingRenames /grant "NT AUTHORITY\SYSTEM:(RX)"
icacls %windir%\winsxs\temp\PendingRenames /grant "NT Service\trustedinstaller:(F)"
icacls %windir%\winsxs\temp\PendingRenames /grant BUILTIN\Users:(RX)
TAKEOWN /f %windir%\winsxs\filemaps\* /a
icacls %windir%\winsxs\filemaps\*.* /grant "NT AUTHORITY\SYSTEM:(RX)"
icacls %windir%\winsxs\filemaps\*.* /grant "NT Service\trustedinstaller:(F)"
icacls %windir%\winsxs\filemaps\*.* /grant BUILTIN\Users:(RX)

net stop cryptsvc
net start cryptsvc

Digite o comando a seguir para verificar se o gravador do sistema está agora listado:
vssadmin list writers

Maiores informações:

https://support.microsoft.com/pt-br/help/2009272/system-state-backup-using-windows-server-backup-fails-with-error-syste