diff --git a/doc/configuration.txt b/doc/configuration.txt
index f397f411c..b28e85198 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -8725,6 +8725,9 @@ each of which has a special meaning :
             would be wise to preventively restart the process after such an
             event too, in case it would be caused by memory corruption.
 
+        D : the session was killed by haproxy because the server was detected
+            as down and was configured to kill all connections when going down.
+
         c : the client-side timeout expired while waiting for the client to
             send or receive data.
 
diff --git a/include/types/session.h b/include/types/session.h
index 7fde0aa71..605492489 100644
--- a/include/types/session.h
+++ b/include/types/session.h
@@ -65,9 +65,9 @@
 #define SN_ERR_PRXCOND	0x00005000	/* the proxy decided to close (deny...) */
 #define SN_ERR_RESOURCE	0x00006000	/* the proxy encountered a lack of a local resources (fd, mem, ...) */
 #define SN_ERR_INTERNAL	0x00007000	/* the proxy encountered an internal error */
-#define SN_ERR_MASK	0x00007000	/* mask to get only session error flags */
+#define SN_ERR_DOWN	0x00008000	/* the proxy killed a session because the backend became unavailable */
+#define SN_ERR_MASK	0x0000f000	/* mask to get only session error flags */
 #define SN_ERR_SHIFT	12		/* bit shift */
-#define SN_BE_TRACK_SC1 0x00008000	/* backend tracks stick-counter 1 */
 
 /* session state at termination, bits values 0x10000 to 0x70000 (0-7 shift 16) */
 #define SN_FINST_R	0x00010000	/* session ended during client request */
@@ -79,9 +79,10 @@
 #define SN_FINST_T	0x00070000	/* session ended tarpitted */
 #define SN_FINST_MASK	0x00070000	/* mask to get only final session state flags */
 #define	SN_FINST_SHIFT	16		/* bit shift */
-#define SN_BE_TRACK_SC2 0x00080000	/* backend tracks stick-counter 2 */
 
-#define SN_IGNORE_PRST	0x00100000	/* ignore persistence */
+#define SN_IGNORE_PRST	0x00080000	/* ignore persistence */
+#define SN_BE_TRACK_SC1 0x00100000	/* backend tracks stick-counter 1 */
+#define SN_BE_TRACK_SC2 0x00200000	/* backend tracks stick-counter 2 */
 
 /* Termination sequence tracing.
  *
diff --git a/src/checks.c b/src/checks.c
index 6b34a377b..5bcf47c5d 100644
--- a/src/checks.c
+++ b/src/checks.c
@@ -371,6 +371,8 @@ static void shutdown_sessions(struct server *srv)
 				buffer_shutw_now(session->req);
 				buffer_shutr_now(session->rep);
 				session->task->nice = 1024;
+				if (!(session->flags & SN_ERR_MASK))
+					session->flags |= SN_ERR_DOWN;
 				task_wakeup(session->task, TASK_WOKEN_OTHER);
 		}
 	}
diff --git a/src/log.c b/src/log.c
index 58d884a54..02b6b20eb 100644
--- a/src/log.c
+++ b/src/log.c
@@ -52,7 +52,7 @@ const char *monthname[12] = {
 	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
 };
 
-const char sess_term_cond[8]  = "-cCsSPRI";	/* normal, CliTo, CliErr, SrvTo, SrvErr, PxErr, Resource, Internal */
+const char sess_term_cond[9]  = "-cCsSPRID";	/* normal, CliTo, CliErr, SrvTo, SrvErr, PxErr, Resource, Internal, Down */
 const char sess_fin_state[8]  = "-RCHDLQT";	/* cliRequest, srvConnect, srvHeader, Data, Last, Queue, Tarpit */
 
 /*