If I boot Ubuntu, restart and then Boot Windows, it will give an error in the boot loader

The answer to your problem is to disable Fast Boot on Windows 8.

To disable it -

All Control Panel items -> Power Options -> System Settings

Click on the 'Change settings that are currently unavailable' link to make the Shutdown options available and Untick the Turn on fast startup option.

The reason for this is explained below with content from this source.

Fast boot explained with an image:

During fast boot the system loads the hiberfile and does not use the files on the filesystem.

So the biggest problem, and the worst problem you can have on a computer, is data loss: if you create a shared NTFS data partition the hibernation may maintain the file structure so if you try to save a file from Linux into the NTFS partition it will get lost on Windows reboot as it only remembers the old file structure. See this Ubuntu Forums thread for more information.

In general: if a disc is mounted when using fast boot, Windows puts this disc and its content in a hiberfile. Any changes made to the system are gone when the hiberfile is restored. This includes mounted external discs. Ubuntu will refuse to mount a disc that has a hiberfile.

One of the bad messages you see in these topics is getting a "disc has errors" when booting Windows.