your phone is root error whay

[arunsin]

Not open Secure Folder why

[bornconfused]

may be you have rooted your phone or your oem is unlocked due to security concerns secure folder is not opening

[xdgone]

this caused for 2 reasons

if you have installed third party bootloader or recovery apart from samsung recovery ( i.e. twrp etc )

if you have rooted your android

To detect

please start your device in download mode and check knox status .

please remember if you have installed or altered stock samsungrecovery than your device will no more support s secure , s health , s pay etc

[arunsin]

tx