--- /dev/null
+commit 8071e8accd250bd1d7758dd16166382b48a6e6d4
+Author: Andrey Volk <andywolk@gmail.com>
+Date: Wed Mar 10 18:37:18 2021 +0300
+
+ NUA handles must be able to unref via stack (nua_handle_unref_user() API) when they are already destroyed or nua is in shutdown
+
+--- a/libsofia-sip-ua/nua/nua.c
++++ b/libsofia-sip-ua/nua/nua.c
+@@ -1165,11 +1165,7 @@ void nua_unref_user(nua_t *nua)
+
+ void nua_handle_unref_user(nua_handle_t *nh)
+ {
+- enter;
+- if (NH_IS_VALID(nh)) {
+- nua_signal(nh->nh_nua, nh, NULL, nua_r_handle_unref, 0, NULL, TAG_NULL());
+- }
+- else {
+- SU_DEBUG_1(("nua: nua_r_handle_unref with invalid handle %p\n", (void *)nh));
+- }
++ assert(nh);
++ nh_enter;
++ nua_signal(nh->nh_nua, nh, NULL, nua_r_handle_unref, 0, NULL, TAG_NULL());
+ }
+--- a/libsofia-sip-ua/nua/nua_common.c
++++ b/libsofia-sip-ua/nua/nua_common.c
+@@ -376,6 +376,8 @@ char const *nua_event_name(nua_event_t e
+ case nua_r_nit_respond: return "nua_r_nit_respond";
+ case nua_r_set_params: return "nua_r_set_params";
+ case nua_r_ack: return "nua_r_ack";
++ case nua_r_handle_unref: return "nua_r_handle_unref";
++ case nua_r_unref: return "nua_r_unref";
+ default: return "NUA_UNKNOWN";
+ }
+ }
+--- a/libsofia-sip-ua/nua/nua_stack.c
++++ b/libsofia-sip-ua/nua/nua_stack.c
+@@ -514,7 +514,7 @@ int nua_signal(nua_t *nua, nua_handle_t
+
+ assert(tend == t); (void)tend; assert(b == bend); (void)bend;
+
+- e->e_always = event == nua_r_destroy || event == nua_r_shutdown;
++ e->e_always = event == nua_r_destroy || event == nua_r_shutdown || event == nua_r_handle_unref || event == nua_r_unref;
+ e->e_event = event;
+ e->e_nh = nh ? nua_handle_ref(nh) : NULL;
+ e->e_status = status;
+@@ -549,10 +549,10 @@ void nua_stack_signal(nua_t *nua, su_msg
+ nua_event_data_t *e = ee->ee_data;
+ nua_handle_t *nh = e->e_nh;
+ tagi_t *tags = e->e_tags;
+- nua_event_t event;
++ nua_event_t event = (enum nua_event_e)e->e_event;
+ int error = 0;
+
+- if (nh) {
++ if (nh && event != nua_r_handle_unref) {
+ if (!nh->nh_prev)
+ nh_append(nua, nh);
+ if (!nh->nh_ref_by_stack) {
+@@ -575,8 +575,6 @@ void nua_stack_signal(nua_t *nua, su_msg
+
+ su_msg_save(nua->nua_signal, msg);
+
+- event = (enum nua_event_e)e->e_event;
+-
+ if (nua->nua_shutdown && !e->e_always) {
+ /* Shutting down */
+ nua_stack_event(nua, nh, NULL, event,