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After installing SafeGuard Disk Encryption for Mac, you are not able to perform an Apple EFI Firmware Update and the following message is shown (in the advanced dialog box):
Your firmware can not be updated because the hard drive partition scheme may not be supported. You must be booted from a GUID partition or RAID scheme. Internal error 28 : 3.
First seen in Sophos SafeGuard Disk Encryption for Mac 5.50.0
The normal method of updating the EFI firmware cannot identify the partition map scheme when Sophos SafeGuard Disk Encryption for Mac is installed.
As of Sophos SafeGuard Disk Encryption for Mac 6.01.0, it is now possible to update the Mac Firmware even when Sophos SafeGuard Disk Encryption for Mac is installed. Please see Sophos SafeGuard Disk Encryption for Mac 6.01.0 Release Notes for further information around how this is possible. There are two available options to update the Apple EFI Firmware on a Sophos SafeGuard Disk Encryption for Mac encrypted computer:
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