Software: Apache 2.4, GSSAPI, CentOS 8

Has anyone had experience configuring fallback login on Elgg using Apache/GSSAPI? Below are my configs in .htaccess file but it returns this error "Additionally, a 401 Unauthorized error was encountered while trying to use an ErrorDocument to handle the request."

    AuthType GSSAPI
    AuthName "SSO Authentication"
    GssapiCredStore keytab:/etc/httpd/krb5.keytab
    GssapiSSLonly On
    Require valid-user
    GssapiBasicAuth On
    GssapiNegotiateOnce On
    ErrorDocument 401 /login
 

Cheers!