Broken Keychain

Have you attempted keychain first aid?

Open Keychain Access

From the drop down menu,

Keychain Access > Keychain First Aid > [Enter your password] > Repair > Start

In Keychain Access,

Edit > Keychain List

Confirm that "System" is checked:

Confirm you actually have a "System" keychain as well in the Keychain Access Sidebar.

Based on your screenshots, either your "System" keychain has been accidentally deleted, or it is located in the wrong place.

The proper path should be:

/Library/Keychains/System.keychain

If it does not exist, we will need to recreate it.

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.

A new, empty System keychain will be created. All stored Wi-Fi network passwords, and possibly other data, will be removed.

If you don't like the results of this procedure, restore from your backup.

Please triple-click anywhere in the line below on this page to select it:

sudo systemkeychain -C

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. I've tested these instructions only with the Safari web browser. If you use another browser, you may have to press the return key after pasting. 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 to be careful. 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 below what you entered. You can then quit Terminal.

Please enter the following command in the same way as before:

ls -@Oaen /L*/Keyc* | pbcopy

The output of the command will be automatically copied to the Clipboard. If the command produced no output, the Clipboard will be empty. Paste into a reply to this message.

Do you still get the error message in your original post?

Please read this whole message before doing anything.

The login screen appears even if you usually login automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.

Test while booted in safe mode. Then reboot in normal mode.