Hi;

I am using Bitlocker on my Win 8.1 Pro, and it works ok when I encrypt my C: drive, I configured my computer to let it prompt for PIN number when I turn on my computer by using the following setting in Group Policy for "Require additional authentication at startup".

Configure TPM startup: Allow TPM

Configure TPM startup PIN: Require startup PIN with TPM

Configure TPM startup key: Allow startup key with TPM

Configure TPM startup key and PIN : Allow startup key and PIN with TPM

I tried it and reboot my computer, it works fine and the computer prompt me for the PIN number after reboot.  However; when I tried to encrypt my USB key or another E: drive partition, I got the error below.  I tried to disable my group policy but no help.

"the group policy settings for BitLocker startup options are in conflict and cannot be applied.

Hi KANE.W,

For BitLocker Group Policy settings, Require additional authentication at startup group policy has conflicts, if one authentication method is required, the other methods cannot be allowed.

Based on your description, I am supposing that in require additional authentication at startup, If you choose to require an additional authentication method, other authentication methods cannot be allowed.

For more information about conflicts of BitLocker group policy

https://technet.microsoft.com/en-us/library/jj679890.aspx?f=255&MSPPError=-2147217396#BKMK_unlockpol1

Regards

D. Wu