Ubuntu installer can't find any disk on Dell XPS 13 9350

1. In Windows, run Command Prompt as admin
2. Invoke a Safe Mode boot with the command: bcdedit /set {current} safeboot minimal
3. Restart the PC and enter your BIOS during bootup.
4. Change from IDE to AHCI mode then Save & Exit.
5. Windows 10 will launch in Safe Mode.
6. Right click the Window icon and select to run the Command Prompt in Admin mode from among the various options.
7. Cancel Safe Mode booting with the command: bcdedit /deletevalue {current} safeboot
8. Restart your PC once more and this time it will boot up normally but with AHCI mode activated.

(Source)

So far the only workaround I found is to switch to AHCI Sata mode in BIOS settings:

1. Boot into BIOS (F12 at startup)
2. Select Bios Setup.
3. Move to System Configuration > SATA Operation and select AHCI.

Restart the computer and now the Ubuntu installer will detect the SSD.

Unfortunately this is not practical for a dual boot setup as Windows won't be able to boot in SATA mode so you every time will have to revert the BIOS settings when wanting to boot Windows.

The main problem is that DELL shipped with Windows pre-installed in IDE mode. The best solution in every aspect is to perform a clean installation of Windows. As a side effect you achieve one big advantage: pure Windows without any crap.

1. Create a Windows system backup before. Things may break badly!
2. Boot from a GParted Live media and format the Windows partition with ntfs.
3. Boot into BIOS/UEFI of the PC and change the settings to AHCI/SATA mode.
4. Reinstall Windows.
5. Disable Hibernation and Fast startup in Windows
6. Boot from Ubuntu installation media and reinstall GRUB.
7. Boot into BIOS and select Ubuntu to be the default operating system to boot. Now you can select which system to boot, without having to change settings.

For those users who don't want to reinstall Windows, there is a way to switch to AHCI mode:

• Windows Vista and 7
• Windows 8/8.1 and 10