diff --git a/src/client.cpp b/src/client.cpp
index 7089582..8ae162e 100644
--- a/src/client.cpp
+++ b/src/client.cpp
@@ -568,7 +568,7 @@ void Context::Pvt::onSearchS(evutil_socket_t fd, short evt, void *raw)
         for(unsigned i=0; i<4 && static_cast<Pvt*>(raw)->onSearch(); i++) {}
 
     }catch(std::exception& e){
-        log_crit_printf(io, "Unhandled error in search Rx callback: %s\n", e.what());
+        log_exc_printf(io, "Unhandled error in search Rx callback: %s\n", e.what());
     }
 }
 
@@ -693,7 +693,7 @@ void Context::Pvt::tickSearchS(evutil_socket_t fd, short evt, void *raw)
     try {
         static_cast<Pvt*>(raw)->tickSearch();
     }catch(std::exception& e){
-        log_crit_printf(io, "Unhandled error in search timer callback: %s\n", e.what());
+        log_exc_printf(io, "Unhandled error in search timer callback: %s\n", e.what());
     }
 }
 
@@ -724,7 +724,7 @@ void Context::Pvt::tickBeaconCleanS(evutil_socket_t fd, short evt, void *raw)
     try {
         static_cast<Pvt*>(raw)->tickBeaconClean();
     }catch(std::exception& e){
-        log_crit_printf(io, "Unhandled error in beacon cleaner timer callback: %s\n", e.what());
+        log_exc_printf(io, "Unhandled error in beacon cleaner timer callback: %s\n", e.what());
     }
 }
 
diff --git a/src/clientconn.cpp b/src/clientconn.cpp
index bac9ddd..4aadf0a 100644
--- a/src/clientconn.cpp
+++ b/src/clientconn.cpp
@@ -402,7 +402,7 @@ void Connection::tickEchoS(evutil_socket_t fd, short evt, void *raw)
     try {
         static_cast<Connection*>(raw)->tickEcho();
     }catch(std::exception& e){
-        log_crit_printf(io, "Unhandled error in echo timer callback: %s\n", e.what());
+        log_exc_printf(io, "Unhandled error in echo timer callback: %s\n", e.what());
     }
 }
 
diff --git a/src/clientintrospect.cpp b/src/clientintrospect.cpp
index 8927833..ceb8c8d 100644
--- a/src/clientintrospect.cpp
+++ b/src/clientintrospect.cpp
@@ -158,7 +158,7 @@ void Connection::handle_GET_FIELD()
         try {
             done(std::move(res));
         }catch(std::exception& e){
-            log_err_printf(setup, "Unhandled exception %s in Info result() callback: %s\n", typeid (e).name(), e.what());
+            log_exc_printf(setup, "Unhandled exception %s in Info result() callback: %s\n", typeid (e).name(), e.what());
         }
 
     } else {
diff --git a/src/clientmon.cpp b/src/clientmon.cpp
index 0c6b36a..83294ec 100644
--- a/src/clientmon.cpp
+++ b/src/clientmon.cpp
@@ -84,7 +84,7 @@ struct SubscriptionImpl : public OperationBase, public Subscription
             try {
                 event(*this);
             }catch(std::exception& e){
-                log_err_printf(io, "Unhandled user exception in Monitor %s %s : %s\n",
+                log_exc_printf(io, "Unhandled user exception in Monitor %s %s : %s\n",
                                 __func__, typeid (e).name(), e.what());
             }
         }
@@ -312,8 +312,8 @@ struct SubscriptionImpl : public OperationBase, public Subscription
         try {
             static_cast<SubscriptionImpl*>(raw)->tickAck();
         }catch(std::exception& e) {
-            log_crit_printf(io, "Unhandled exception in %s %s : %s\n",
-                            __func__, typeid (e).name(), e.what());
+            log_exc_printf(io, "Unhandled exception in %s %s : %s\n",
+                           __func__, typeid (e).name(), e.what());
         }
     }
 };
diff --git a/src/conn.cpp b/src/conn.cpp
index 0441e7c..4d350e3 100644
--- a/src/conn.cpp
+++ b/src/conn.cpp
@@ -219,7 +219,7 @@ void ConnBase::bevEventS(struct bufferevent *bev, short events, void *ptr)
     try {
         conn->bevEvent(events);
     }catch(std::exception& e){
-        log_crit_printf(connsetup, "%s %s Unhandled error in bev event callback: %s\n", conn->peerLabel(), conn->peerName.c_str(), e.what());
+        log_exc_printf(connsetup, "%s %s Unhandled error in bev event callback: %s\n", conn->peerLabel(), conn->peerName.c_str(), e.what());
         conn->cleanup();
     }
 }
@@ -230,7 +230,7 @@ void ConnBase::bevReadS(struct bufferevent *bev, void *ptr)
     try {
         conn->bevRead();
     }catch(std::exception& e){
-        log_crit_printf(connsetup, "%s %s Unhandled error in bev read callback: %s\n", conn->peerLabel(), conn->peerName.c_str(), e.what());
+        log_exc_printf(connsetup, "%s %s Unhandled error in bev read callback: %s\n", conn->peerLabel(), conn->peerName.c_str(), e.what());
         conn->cleanup();
     }
 }
@@ -241,7 +241,7 @@ void ConnBase::bevWriteS(struct bufferevent *bev, void *ptr)
     try {
         conn->bevWrite();
     }catch(std::exception& e){
-        log_crit_printf(connsetup, "%s %s Unhandled error in bev write callback: %s\n", conn->peerLabel(), conn->peerName.c_str(), e.what());
+        log_exc_printf(connsetup, "%s %s Unhandled error in bev write callback: %s\n", conn->peerLabel(), conn->peerName.c_str(), e.what());
         conn->cleanup();
     }
 }
diff --git a/src/evhelper.cpp b/src/evhelper.cpp
index e400d65..48f9518 100644
--- a/src/evhelper.cpp
+++ b/src/evhelper.cpp
@@ -133,7 +133,7 @@ struct evbase::Pvt : public epicsThreadRunable
             log_printf(logerr, lvl, "Exit loop worker: %d for %p\n", ret, base.get());
 
         }catch(std::exception& e){
-            log_crit_printf(logerr, "Unhandled exception in event_base run : %s\n",
+            log_exc_printf(logerr, "Unhandled exception in event_base run : %s\n",
                             e.what());
             start_sync.trigger();
         }
@@ -154,7 +154,7 @@ struct evbase::Pvt : public epicsThreadRunable
                     Guard G(lock);
                     *work.result = std::current_exception();
                 } else {
-                    log_crit_printf(logerr, "Unhandled exception in event_base : %s : %s\n",
+                    log_exc_printf(logerr, "Unhandled exception in event_base : %s : %s\n",
                                     typeid(e).name(), e.what());
                 }
             }
@@ -169,7 +169,7 @@ struct evbase::Pvt : public epicsThreadRunable
         try {
             self->doWork();
         }catch(std::exception& e){
-            log_crit_printf(logerr, "Unhandled error in doWorkS callback: %s\n", e.what());
+            log_exc_printf(logerr, "Unhandled error in doWorkS callback: %s\n", e.what());
         }
     }
 
diff --git a/src/log.cpp b/src/log.cpp
index e0813e8..cf6df44 100644
--- a/src/log.cpp
+++ b/src/log.cpp
@@ -15,7 +15,9 @@
 #include <pvxs/log.h>
 
 #include <envDefs.h>
+#include <dbDefs.h>
 #include <osiSock.h>
+#include <epicsStackTrace.h>
 #include <epicsString.h>
 #include <epicsAssert.h>
 #include <epicsStdio.h>
@@ -65,6 +67,13 @@ const char* log_prefix(const char* name, Level lvl)
     return prefix;
 }
 
+void log_stacktrace()
+{
+    // stack traces can be long.  flush to reduce truncation
+    errlogFlush();
+    epicsStackTrace();
+}
+
 } // namespace detail
 
 namespace {
diff --git a/src/pvxs/log.h b/src/pvxs/log.h
index e37553f..c048d6d 100644
--- a/src/pvxs/log.h
+++ b/src/pvxs/log.h
@@ -51,6 +51,9 @@ namespace detail {
 PVXS_API
 const char* log_prefix(const char* name, Level lvl);
 
+PVXS_API
+void log_stacktrace();
+
 } // namespace detail
 
 //! Define a new logger global.
@@ -82,6 +85,13 @@ void xerrlogHexPrintf(const void *buf, size_t buflen);
 #define log_info_printf(LOGGER, ...)  log_printf(LOGGER, ::pvxs::Level::Info, __VA_ARGS__)
 #define log_debug_printf(LOGGER, ...) log_printf(LOGGER, ::pvxs::Level::Debug, __VA_ARGS__)
 
+#define log_exc_printf(LOGGER, FMT, ...)   do{ \
+    if((LOGGER).test(::pvxs::Level::Crit)) { \
+        errlogPrintf("%s " FMT, ::pvxs::detail::log_prefix((LOGGER).name, ::pvxs::Level::Crit), __VA_ARGS__); \
+        ::pvxs::detail::log_stacktrace(); \
+    } \
+}while(0)
+
 #define log_hex_printf(LOGGER, LVL, BUF, BUFLEN, FMT, ...) do{ if((LOGGER).test(LVL)) { \
         xerrlogHexPrintf(BUF, BUFLEN); \
         errlogPrintf("%s " FMT, ::pvxs::detail::log_prefix((LOGGER).name, LVL), __VA_ARGS__); } \
diff --git a/src/server.cpp b/src/server.cpp
index b65c360..062d95e 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -441,7 +441,7 @@ void Server::Pvt::onSearch(const UDPManager::Search& msg)
             try {
                 pair.second->onSearch(searchOp);
             }catch(std::exception& e){
-                log_err_printf(serversetup, "Unhandled error in Source::onSearch for '%s' : %s\n",
+                log_exc_printf(serversetup, "Unhandled error in Source::onSearch for '%s' : %s\n",
                            pair.first.second.c_str(), e.what());
             }
         }
@@ -554,7 +554,7 @@ void Server::Pvt::doBeaconsS(evutil_socket_t fd, short evt, void *raw)
     try {
         static_cast<Pvt*>(raw)->doBeacons(evt);
     }catch(std::exception& e){
-        log_crit_printf(serverio, "Unhandled error in beacon timer callback: %s\n", e.what());
+        log_exc_printf(serverio, "Unhandled error in beacon timer callback: %s\n", e.what());
     }
 }
 
diff --git a/src/serverchan.cpp b/src/serverchan.cpp
index 27a4a37..ab7f1ab 100644
--- a/src/serverchan.cpp
+++ b/src/serverchan.cpp
@@ -224,7 +224,7 @@ void ServerConn::handle_SEARCH()
             try {
                 pair.second->onSearch(op);
             }catch(std::exception& e){
-                log_err_printf(serversetup, "Unhandled error in Source::onSearch for '%s' : %s\n",
+                log_exc_printf(serversetup, "Unhandled error in Source::onSearch for '%s' : %s\n",
                            pair.first.second.c_str(), e.what());
             }
         }
@@ -311,7 +311,7 @@ void ServerConn::handle_CREATE_CHANNEL()
                         break;
                     }
                 }catch(std::exception& e){
-                    log_err_printf(connsetup, "Client %s Unhandled error in onCreate %s,%d %s : %s\n", peerName.c_str(),
+                    log_exc_printf(connsetup, "Client %s Unhandled error in onCreate %s,%d %s : %s\n", peerName.c_str(),
                                pair.first.second.c_str(), pair.first.first,
                                typeid(&e).name(), e.what());
                 }
diff --git a/src/serverconn.cpp b/src/serverconn.cpp
index 0417563..5da38fe 100644
--- a/src/serverconn.cpp
+++ b/src/serverconn.cpp
@@ -388,7 +388,7 @@ void ServIface::onConnS(struct evconnlistener *listener, evutil_socket_t sock, s
         auto conn(std::make_shared<ServerConn>(self, sock, peer, socklen));
         self->server->connections[conn.get()] = std::move(conn);
     }catch(std::exception& e){
-        log_crit_printf(connsetup, "Interface %s Unhandled error in accept callback: %s\n", self->name.c_str(), e.what());
+        log_exc_printf(connsetup, "Interface %s Unhandled error in accept callback: %s\n", self->name.c_str(), e.what());
         evutil_closesocket(sock);
     }
 }