If the eDrive creation processes fails near the beginning (during the partitioning stage), there is likely a volume structures issue on the destination drive. If the failure occurs later, then there is likely a problem with the user account that is active when the eDrive is being created, since that is the user account being copied to the eDrive. This can often be addressed by resetting the ACLs of that user account (similar to repairing permissions, but not achieved by repairing permissions in Disk Utility or TechTool Pro).

To reset the ACL's (Access Control Lists) for a user account, you will first need to start up from your Recovery HD by holding Command-R at startup. Once you see the Mac OS Utilities window, click on the Utilities Menu, and choose Terminal. At Terminal's command prompt type 'resetpassword' (no quotes, all lower case), to open the Reset Password utility. Once it has opened, select your user account and then click the Reset ACLs button to set the permissions for your user account to their default values. When that has finished, quit the Reset Password utility, and then restart normally.

This procedure applies to Mac OS X versions 10.8 and later. A similar procedure can be followed by starting up from your Mac OS X startup DVD or the Recovery HD in 10.7 and choosing the Reset Password utility from the Utilities menu.