I have a Dell Latitude 7400 and want to install Ubuntu 19.04. When in the install menu, I don't see its SSD, only my current USB drive. Windows 10 is installed on this laptop, but I don't see it. What could be cause of this problem?
The problem is a known limitation when working with Intel RST and the
AHCI+RAID mode set by default in the BIOS/firmware on newer systems (especially Dells).
This is Intel Rapid Storage technology, but Ubuntu can't work with it. In the firmware of the system you have to disable the
AHCI+RAID SATA mode and switch it to just
AHCI mode. That will let Ubuntu see the drive.
BE WARNED! If you intend to access the Windows OS at some point, you'll have to switch back to
AHCI+RAID in the BIOS/firmware, or you'll have to convert Windows' AHCI+RAID install to just AHCI - using a guide such as this one on thinkcritical.com. Otherwise, Windows will fail to boot. (Because fixing Windows is offtopic here however I'm not going to go into detail on how to fix this here)