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To fix the issue, do the steps below please.
Go to System Preferences > iCloud and turn off "Keychain" option there if it turned on. If it is off already, then sign out from iCloud from there.
Then go to Applications > Utilities folder and open Keychain Access.
From the Keychain Access menu, choose Preferences.
Click General, then click Reset My Default Keychain.
Authenticate with your account login password *****
Quit Keychain Access.
Then open Safari, click on Safari menu and select Clear History and Website Data. Select All History and clear it. Then go to System Preferences > iCloud and sign in back to your account. This should fix the problem.
Please let me know if that didn't work, so we can continue troubleshooting.