I also met the same error(in kilo branch). keystone.log indicated it's 'fernet' related.
After I changed variable 'keystone_token_provider' to 'keystone.token.providers.uuid.Provider'. The issue resolved.
I also met the same error(in kilo branch). keystone.log indicated it's 'fernet' related.
After I changed variable 'keystone_ token_provider' to 'keystone. token.providers .uuid.Provider' . The issue resolved.