Samsung announced the closure of the security apps, my Samsung My Knox App, early this year, through sending email to the users of this app, Here is the official email i received from Samsung.
Thank you for using My Knox.
As previously announced, we will end support for My Knox on 19th December 2017. You will not be able to download My Knox from any app store after the end-of-service date.
You may use My Knox on your mobile device until you uninstall the application. However, you will be unable to log in to the My Knox portal to remotely manage your device (e.g. to reset your My Knox password or unlock My Knox).
If you have a phone that runs the Android N OS, we recommend transferring your private data in My Knox to Secure Folder*, available at Google Play or Galaxy Apps, and on new Samsung phones such as the Galaxy Note 8. We also recommend backing up your My Knox data first, and restoring the data after you set up Secure Folder.
To back up My Knox data, go to My Knox Settings > Backup and restore > Back up My Knox data. Please note that a Samsung account is required to use the My Knox backup and restore feature.
If your phone does not support Secure Folder, then please back up the content to outside My Knox (e.g. using the Move to Personal mode feature).
For more information about My Knox termination, please visit My Knox FAQ .
We hope you have enjoyed your experience with My Knox. Samsung is committed to continuous innovation to give you the highest-quality products and services.
* The availability of Secure Folder varies, depending on region and carrier, even for N OS devices.
The Samsung My Knox Team