My Macbook will not start like it normally does, it says update required. What is wrong?

Question

My macbook says "update required" everytime i turn it on. It just shows me a grey screen and then I have to log in with my password. I cannot see my account picture either. What to do? I have recently reset my Macbook.

Answer 1

Back up all data.
If you have more than one user account, you must be logged in as an administrator to carry out these instructions. I've tested them only with the Safari web browser. If you use another browser, they may not work as described.
Triple-click anywhere in the line below on this page to select it:
sudo fdesetup sync
Copy the selected text to the Clipboard by pressing the key combination command-C.
Launch the Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.
Paste into the Terminal window by pressing the key combination command-V. You'll be prompted for your login password. Nothing will be displayed when you type it. If you don’t have a login password, you’ll need to set one before you can run the command. You may get a one-time warning not to screw up. Confirm. You don't need to post the warning.
If you see a message that your username "is not in the sudoers file," then you're not logged in as an administrator. Log in as one and start over.
Wait for a new line ending in a dollar sign (“$”) to appear. You can then quit Terminal. Test.