HI, I believe i have come across a defect in the OIDCAttributeMapperHelper class. The issue occurs when you have a String Attribute which is set with no value using a custom federation provider. The code blows up on the line: return attributeValue.toString(); (Line 64) in the section of code: String type = mappingModel.getConfig().get(JSON_TYPE); if (type == null) return attributeValue; if (type.equals("boolean")) { if (attributeValue instanceof Boolean) return attributeValue; if (attributeValue instanceof String) return Boolean.valueOf((String)attributeValue); throw new RuntimeException("cannot map type for token claim"); } else if (type.equals("String")) { if (attributeValue instanceof String) return attributeValue; return attributeValue.toString(); } else if (type.equals("long")) { if (attributeValue instanceof Long) return attributeValue; if (attributeValue instanceof String) return Long.valueOf((String)attributeValue); throw new RuntimeException("cannot map type for token claim"); } else if (type.equals("int")) { if (attributeValue instanceof Integer) return attributeValue; if (attributeValue instanceof String) return Integer.valueOf((String)attributeValue); throw new RuntimeException("cannot map type for token claim"); } return attributeValue; The attribute exists with no value which causes the attrbuteValue to be null and there is no check for null at that point. I would expect it would return empty string if the type is string and the value is null. Thanks, jeff _______________________________________________ keycloak-user mailing list keycloak-user(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/keycloak-user