High sierra issues can anyone help me?

Hi stucchi1,

Can you please take a screenshot or a photo of the screen that is displaying this error message? I myself haven't ran into this yet, but I suspect that FileVault may be the reason why this message is appearing.

To take a partial screenshot on your Mac, press Command-Shift-4. Drag your cursor to select a rectangular area to capture, then release the mouse or trackpad. Alternatively, to take a screenshot of a specific window, press the space bar (after pressing Command-Shift-4), then click on the window you want to capture. Your screenshot will be saved onto your desktop.

To take a screenshot of the entire screen, press Command-Shift-3. Your screenshot will be saved onto your desktop.

Or, if you want to use the actual application for this, navigate to the Utilities folder inside the Applications folder, then open Grab. It's basically the Mac version of Windows Snipping Tool. To use it, click on Capture in the very top menu bar once it's open (no GUI will display), then choose the type of screenshot you'd like to take.

If you need to obscure or block any sensitive information in the screenshot(s), please read this User Tip: How to edit a screenshot. The circled marker (Markup) icon replaces the toolbox icon in Preview, but has the same function.

On your orignal Mac OS go to System preferences, Security and Privacy and under Filevault turn that off to stop encryption. Once completed and you have the new O.S. installed you can turn it on so all files will be encrypted.