Folders kept after factory reset?!

[AgentSuave]

Hi,
I sold this phone a few days ago, so I did a factory reset, apps were gone, welcome screen appeared, all was well, but I noticed that some folders in internal storage weren't wiped, like the the Camera, Pictures, Downloads, and a few others, so I wiped them myself.
But only after selling it I forgot to check the whatsapp folder, which isn't in the storage root anymore, but at <storage>/Android\media\com.whatsapp.
Does the Android\media\ folder gets unequivocally wiped in a factory reset? Because although the whatsapp app was gone from the homescreen, I don't want other people checking my pictures in that folder, or those pictures to appear once they install whatsapp.

I used the factory reset through the settings app, and then it rebooted to the recovery to wipe the phone, however the recovery wasn't the original but TWRP. Is this significant?

 

[gogocar62]

If you did a "factory reset" in TWRP, the files on the device were not deleted. You should have done a "Format Data" in TWRP. Then the phone will reset and format the data partition.

 

[AgentSuave]

I didn't know it then, also the process was automatic, meaning when I ran the factory reset from MIUI settings and confirmed all the warnings -- saying that all my stuff including photos and documents would be erased, which didn't happen -- It rebooted, went to recovery (TWRP), and it just ran a wipe script with the only input from me being the security PIN, and then it rebooted again to system. It didn't present me the TWRP options, much less letting me do anything else there.

But hey, "factory reset" is a device state as it was once it get out of the factory, aka *completely clean* so I trusted it. Also I was in a hurry to sell the phone to someone that was already waiting for me. At least I realized in time and manually deleted almost all the folders, but it never occurred me the Android/media/com.whatsapp.

At least I'm almost certain that reinstalling whatsapp with a different number won't enable the new user to check previous photos and voice messages from me. But they'll remain there in that folder, and I don't know if whatsapp will ever do any cleaning for files that don't belong to the new user account, and I'm really not ok with that. If the user is savvy enough to browse folders and check that particular folder (it may require some whatsapp photo that he has there), it will eventually see my stuff. If he does a google backup of whatsapp, my stuff could be uploaded to google, and all because to some vendors, factory reset is just a glorified system cleaning.

I don't know why I had to be put through 4 warnings and confirmation dialogs about loosing all my stuff *including photos, docs and music*, it nothing was wiped.
This is unacceptably bad programming either from xiaomi or Trwp, and I will never trust these guys again.

Anyway, thanks for the answer.

 

[gogocar62]

The procedure you describe will work without any problems if the device has stock recovery.
If you are using a custom ROM and custom recovery (TWRP/OR etc.), you should read up on this.

I don't know why I had to be put through 4 warnings and confirmation dialogs about loosing all my stuff *including photos, docs and music*, it nothing was wiped.
This is unacceptably bad programming either from xiaomi or Trwp, and I will never trust these guys again.

Because the system relies on stock recovery.