Applies to:

Windows Small Business Server 2011 Essentials, Windows Home Server 2011, Windows Storage Server 2008 R2 Essentials, Windows Server 2012 Essentials. 

Symptoms:
 
After client BMR for UEFI machine finishes, the UI shows that the process fails.
Check the log, found the following message: 
    Formatting ESP partition at offset 0x12d00000 
    ERROR: FormatPartitionEx failed, error 0x80042405
This error will appear when user perform BMR operation for UEFI machine in advanced mode when the offset of EFI partition in disk does not equal to the value in chosen client backup set. 
 
 
Cause:

Currently, the BMR process will format the ESP partition using the offset from the backup set. And it will fail when this offset differs from the current disk layout.
This applies to Windows Server 2012 Essentials, Windows Home Server 2011, Windows Small Business Server 2011 Essentials, Windows Storage Server 2011 with UEFI-GPT hotfix. 

Solution: 
 
Check the log, find the ESP partition offset info (in hexadecimal), and calculate the offset for ESP partition.
For example, if the value from log is 0x12d00000 (315621376 in decimal), start powershell in another machine, type the following command and press Enter: 
    0x12d00000/1024/1024–1
The offset of ESP partition will be shown on the screen (300 in this case).
User should create a 300MB primary partition (It’s for system reserved or OEM partition purpose, and to make the EFI partition lay on the correct offset) at the leftmost area of the disk using diskpart, then create the EFI and MSR partition, and finally the primary partition for your system drive. After that, map your system volume to the volume in this disk.
So the steps for diskpart should be: 
 
    Diskpart 
    Select disk 0 
    Clean 
    Convert gpt 
    Create partition primary size=300 
    Create partition efi size=100 
    Create partition msr size=128 
    (Create your other primary partition after that) 

For other steps, please refer to Client BMR user help file from wizard.