There are several possible causes for this issue. Please take each of the following steps that you haven't already tried, testing after each one, until it's resolved. Back up all data before making any changes.
Step 1
Launch the Keychain Access 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 and start typing the name.
Select the iCloud keychain from the list on the left side of the Keychain Access window. If your default keychain has a different name, select that.
If the lock icon in the top left corner of the window shows that the keychain is locked, click to unlock it. You'll be prompted for the keychain password, which is the same as your login password.
Select
Keychain Access ▹ Keychain First Aid
from the menu bar and repair the keychain.
Step 2
Open the iCloud preference pane and uncheck the Keychain box. You'll be prompted to delete the local iCloud keychain. Confirm. Then re-check the box. Follow one of the procedures described in this support article to set up iCloud Keychain on an additional device.
Step 3
Triple-click the line below on this page to select it, then copy the text to the Clipboard by pressing the key combination command-C:
~/Library/Keychains
In the Finder, select
Go ▹ Go to Folder...
from the menu bar and paste into the box that opens by pressing command-V. You may not see what you pasted because a line break is included. Press return. A folder named "Keychains" should open. There should be a file in that folder with the name "login.keychain". If there is also a file iwith the name "login_renamed_1.keychain", then please do as follows:
☞ Rename login.keychain to "login-old.keychain".
☞ Rename login_renamed_1.keychain to "login.keychain".
You can then close the folder.
Delete the login keychain from the keychain list in Keychain Access. Choose
Delete References
when prompted, not Delete References & Files.
Select
File ▹ Add Keychain...
from the menu bar. Add back the file now named "login.keychain". If any of your needed keychain items are missing from it, also add back the file now named "login-old.keychain". I suggest you transfer any needed items from that keychain to the login keychain, then delete it. The transfers are made by drag-and-drop in Keychain Access. You'll need to enter your password for each item transferred.
Run Keychain First Aid again. Quit Keychain Access.
