Please note that every attribute in attribute-map.xml with result in a header sent to backend if ShibUseHeaders is enabled (two if metadataAttributePrefix is defined). The limit on number of request headers and size of the request header may have to be modified in backends If you get too many, remove unused attributes from attribute-map.xml or modify backend header limits (LimitRequestFields/LimitRequestFieldSize in Apache HTTPD Server, maxHeaderCount/maxHttpHeaderSize in Apache Tomcat Connectors).