Not been able to figure out why this happens, but this fixes it ....
Index: hostapd-2021-05-21-d98f4c46/src/ap/ieee802_1x.c
===================================================================
--- hostapd-2021-05-21-d98f4c46.orig/src/ap/ieee802_1x.c
+++ hostapd-2021-05-21-d98f4c46/src/ap/ieee802_1x.c
@@ -606,7 +606,7 @@ int add_common_radius_attr(struct hostap
return -1;
for (attr = req_attr; attr; attr = attr->next) {
- if (!radius_msg_add_attr(msg, attr->type,
+ if (attr->type && !radius_msg_add_attr(msg, attr->type,
wpabuf_head(attr->val),
wpabuf_len(attr->val))) {
wpa_printf(MSG_ERROR, "Could not add RADIUS attribute");