For example, this can occur in multi-disk configurations, or if the BCD store has been repaired. If reagentc.exe /disable succeeds, a subsequent enable command should also succeed.
Normally, you use the reagentc.exe /disable command to uninstall WinRE in this scenario. The reagentc.exe /disable command looks at the BCD store to determine where the boot.sdi file was installed to, and will remove it. However, in scenarios where the BCD store is no longer intact, the command cannot locate boot.sdi and will fail.
Delete the \recovery\winre\boot.sdi from the previous WinRE installation.
Reagentc.exe /enable command will now succeed. Please reference WinRE documentation for further information on reagentc.exe.