THIS WORKED FOR ME, and EASY:
Go to the Samsung store, this is an app in your list of apps. I'd never even used it before...
Once there, look for the app SecureFolder (do a search).
When it comes up just click on the REFRESH button or maybe it's a download button or maybe it means to re-download. It's a button that has a spiral circle with an arrow like in Windows would mean "refresh".
I clicked on that and it re-installed the app and solved everything, my pictures and documents and password remaining in place!
But the question is, "WHY is the Samsung firmware breaking our securefolder app? And are they going to fix this bug? How do we report it to them so they can fix it?
Thank you for that information. We would recommend having a certified repair technician to evaluate the device.
You can walk in to the service location at your local ubreakifix, where they can assist you further.
You can locate the nearest location by visiting: https://www.ubreakifix.com/locations
Hi, I had the same problem with my J7 Neo. But I think I figured out how to fix the problem. First I apply the hard reset. Then I go to the Galaxy Store, which is the icon pre-installed on the phone and look for Secure Folder app, there you will find an update. Finally, applied the update. At the beginning It seems that it's not working out because the OPEN button doesn't work. Close all the windows and open the secure folder from the toolbar. It worked with my phone. I hope this helps you fix the problem.
The April 1st 2019 security update broke the Secure Folder feature on my Samsung J7.
Factory reset didn't fix it. The latest system firmware is bad.