Hi,

To get a better clarity about the issue, please provide the details below:

1. Are you upgrading to Windows 10 for the first time?
2. Do you receive any error message?

Meanwhile, I suggest you to refer to the thread below and check if it helps.

http://answers.microsoft.com/en-us/windows/forum/windows_10-windows_install/windows-10-upgrade-assistant-is-stuck-at-99/1708a411-3255-4bec-804a-d2553f2fd645

Please post back if you need further assistance, we will be happy to assist you.

Thank you.

If the Windows 10 Upgrade Assistant becomes stuck or unresponsive at various percentages: 0%, 32%, 62%, 87%, 99%, please wait at least 4 to 7 hours. If you are updating through Windows Update, when the download reaches 99% disconnect from the Internet LAN (Ethernet) or Wi-Fi then proceed with the installation.

If setup does not progress, close the wizard then restart your computer. Follow the instructions to upgrade manually using the Media Creation Tool or the Windows 10 ISO file.

How to download official Windows 10 ISO files

How to: upgrade from previous versions of Windows using Windows 10 ISO file

If setup did not complete on time and you experience problems activating. Contact Chat support after the Windows 10 installation is complete. Click Start > All Apps > Contact Support. Explain your situation to the chat agent.

Activate Your Windows 10 License via Microsoft Chat Support