Redmine

my company used saml as sso service, today i installed redmine_omniauth_saml on my redmine system(2.6.1), but when i login via saml system will display: 422 Invalid form authenticity token. the log in webrick is attached.

rb file in C:\ruby200\redmine-2.6.1\config\initializers:

RedmineSAML = HashWithIndifferentAccess.new(
:assertion_consumer_service_url => "http://localhost:3000", # The redmine application hostname
:issuer => "saml-redmine", # The issuer name
:idp_sso_target_url => "https://uat-sso.abc.com/cas/login", # SSO login endpoint
:idp_cert_fingerprint => "XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX", # SSL fingerprint
:name_identifier_format => "urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress",
:logout_admin => "https://uat-sso.abc.com/cas/logout", # SSO logout URL
:attribute_mapping => { # How will we map attributes from SSO to redmine attributes
:login => 'extra.raw_info.username',
:firstname => 'extra.raw_info.first_name',
:lastname => 'extra.raw_info.last_name',
:mail => 'extra.raw_info.personal_email'
}

please tell me how to fix this issue, thanks all of your great support!