I know this HOWTO is for a different device, but Windows not detecting a phone in fastboot mode is a rather frequent problem and the solution depends on Windows and not so phone model. So the steps described there should help you, too.
Thank you for your answer, much appreciated.
Unfortunately your link doesn’t help me: I’ve already perform that step unsuccessfully. The “Google, Inc. - Other hardware - Android Bootloader Interface” driver doesn’t show up in the list of available drivers on my computer unfortunately.
Do you have any other idea/suggestion to help my Windows detecting my S9?
I’m not 100% sure because I’m not using Windows and can’t check how it’s supposed to look.
But in your case it’s shown as “Android ADB Interface” while the HOWTO mentions “Android Bootloader Interface”.
So if I interpret that correctly, your phone is in the wrong mode. When adb commands work, fastboot commands don’t and vice versa.
I don’t know enough about Samsung devices but maybe you can find some useful hints in this topic: Know your hardware - Samsung
Probably the “Your first boot into TWRP” section contains what you need.
Samsung has Download mode in place of Fastboot, so until you have a Custom ROM you don’t have Fastboot. Samsung calls Download mode Odin mode, which gives the clue to Windows users that you have to use Odin.
The Starlte install includes the wording: “Samsung devices come with a unique boot mode called “Download mode”, which is very similar to “Fastboot mode” on some devices with unlocked bootloaders.” Sorry, but I don’t have the experience to argue with some devices.
When I read my first comment here and the way that I tagged you in, and look at the Install TWRPsource, I see that the OP’s TWRP link is actually quite newly edited. The way that I made my comment now looks insensitive. For that insensitivity I apologise. I had not logged in on Sunday, and seeing this thread I felt perhaps I could add something for the OP in a couple of minutes before an early start.
Now I think you are driving at improving documentation? I am certainly in favour of that and will share my very limited knowledge if you ask.
@manoj, I copy you in because your name appears on the page in question, and I was unable to access a New Topic under “Documentation suggestions + TWRP tag”.
The Install TWRP page linked in the OP is challenged due to it contradicting our other Samsung install documentation.
On most/all Samsung devices the instructions will fail at some point (the actual point may vary with device.)
It seems appropriate to flag this page as unsuitable for Samsung devices. What would be the best way to do that?
Here is a suggestion
This method will work with devices with a standard Fastboot interface. It is not expected to work with any of the /e/ supported Samsung devices which have the “Odin mode”, Download mode, in place of a standard Fastboot interface.