Access to the BCD store is likely to be restricted if attempting to access it from within Windows as it will (in the majority of cases) be open and in use as the system store - this is discussed in more detail here. The BCD store is effectively locked when Windows is booted, however this is not the case when WinPE (Windows Preinstallation Environment) is booted and the store can be copied without any difficulty using WinPE.
Alternative methods for backing up locked system files are available. The following topic "Copy locked system files tis now possible?" on reboot.pro lists a range of software including -
To backup a BCD Store currently in use as the System Store, enter the command bcdedit.exe /export C:\BCD.bak [enter] - where C:\BCD.bak is the backup file (with path) to create. According to available documentation the /export command only works with the system store.
If a system store is not in use then you will need to manually locate the BCD store to back it up. NOTE – The BCD Store (#:\Boot\BCD) is a hidden system file. It is not displayed by default, in order to locate and copy it you will need to open Explorer and select the Organize menu, then select Folder and search options and open the View tab.
Depending on your particular setup you may also need to create a mount point (allocate a drive letter) for the active partition containing the BCD store.
Once the BCD store has been located it can be copied to another location. If you receive an error message whilst copying (e.g. The action can't be completed because the file is open in System) then the store is likely to be in use as the system store.