E: [libfs_mgr] failed to mount /sdcard:

[Anonymous]

I receive this message in recovery when I go back of log menu.

E: [libfs_mgr] failed to mount /sdcard: 

Do you think that a recovery will fix the problem or it's very bad and the device will brick?

My N20 Ultra is new from samsung website, whitout any rooted mod, and I don't have computer access for an emergency debug .. 

[Axton]

Please unmount the SD card from Settings app and tap Device care → Storage → 3 dots → Storage settings → SD card → Unmount. Then, remove and re-insert the SD card after rebooting the phone, check if you still get the same error.

[Anonymous]

There is no SD card in the phone and I never used the slot, maybe this is why I don't see the three dots? Finally, I have find this but ... 😔 https://us.community.samsung.com/t5/Tablets/Update-corrupted-samsung-galaxy-tab-a/td-p/1938008

[RedDogRabbit]

Why did you Boot into Recovery, or did your Note 20 Boot into Recovery on it's own?

If you don't have an external sd card installed, then just Reboot the device, and while you are in Recovery, might as well Wipe the Cache.

Let us know if your Note boots normally. 

[Anonymous]

Yes, the phone boot and work normally and the cache have been flashed (this is why I go in the reco) but the code appear always.

[RedDogRabbit]

That is more likely to just be a normal message. Since you don't have an external sd card (I've always had one, so I've never seen the message), so when you Boot into Recovery, the system does a check, sees that there's no sd card & just reports it on the bottom of the Recovery Menu. 

I wouldn't worry about it at all 👍

Just enjoy your new device 😊

[RedDogRabbit]

They don't need to unmount the sd card, just power off the device, wait a couple of seconds & remove it. 

It would be great if they did have a computer with a micro sd card adapter, so that they could scan the sd card for any errors though.

You would only ever need to unmount the sd card, if you were planning on removing it from a device with the power on, same as if you have your phone connected to a computer, you either want to unmount the phone from the computer before disconnecting the USB cable, or just power off either device and disconnect the cable 😉