How to prevent dialog "Enter password for keyring Default keyring to unlock" always pop-up

To prevent the dialog "Enter password for keyring 'Default keyring' to unlock" always pop-up, you can assign a blank password to keyring.

Be careful - 
By choosing to use a blank password, your stored passwords will not be safely encrypted. They will be accessible by anyone with access to your files.

Run Setting - Passwords and Keys

Right click "Default keyring" and "Change Password"

Enter old password

Leave blank in new password