When attempting to clone using Acronis True Image HD 2015 on some systems running a UEFI, it is possible for the software to be prevented from entering the correct environment to begin the clone. This is usually caused by settings in the UEFI restricting what your computer will boot to when first powered up, causing either error messages or just booting back into Windows without continuing the cloning process. If you are experiencing this type of issue one solution is to create bootable Acronis media with a USB drive or CD/DVD. This media can then be used to start a clone outside of Windows, which will allow you to configure and begin the cloning process without needing to restart the system, avoiding the issue all together. Instructions on how to create bootable Acronis media can be foundhere.
To boot to your Acronis media, it may be necessary for you to press a specific key on your keyboard while the system is booting to interrupt its normal startup process and make the system boot to a specific device. To find the key you need to press during startup, you can check your system or motherboard's owner's manual, or follow any onscreen prompts when your system powers up to enter the UEFI or boot menu to select a boot device. In a boot option menu you will choose to boot to either the disk or flash drive that you created, or in a boot sequence change the order of devices to boot from, prioritizing your USB/optical media ahead of connected hard drives and SSDs.
You will then be presented with a screen asking you to select what you would like to do with numbers next to the options you can select. At this screen you will just need to press the number '1' key on your keyboard to boot into the Acronis software. Once the software is fully loaded you will select 'Tools and Utilities', and then select 'Clone Disk' on the next screen. You should then be presented with a screen asking you to select your source hard drive, then your target drive. Once you have selected the appropriate drives you can then click proceed and start the clone.
A UEFI setting called Secure Boot can also cause similar problems. This setting will usually be found in a Security or Boot category in your BIOS or UEFI (check you documentation for detailed guidance). Once you have located this setting, you will want to change the value from enabled to disabled. After this setting has been disabled you can retry the clone within Windows, or try the bootable media detailed above if you still have difficulty with the cloning software.