diff --git a/src/iperf.h b/src/iperf.h
index a5eea4237..f28b07190 100644
--- a/src/iperf.h
+++ b/src/iperf.h
@@ -204,6 +204,7 @@ struct iperf_stream
     int       remote_port;
     int       socket;
     int       id;
+    int       thread_number;
     int       sender;
 	/* XXX: is settings just a pointer to the same struct in iperf_test? if not,
 		should it be? */
diff --git a/src/iperf_api.h b/src/iperf_api.h
index 20f7cc55a..eaa66cfbd 100644
--- a/src/iperf_api.h
+++ b/src/iperf_api.h
@@ -476,6 +476,7 @@ enum {
     IEPTHREADJOIN=152,		// Unable to join thread (check perror)
     IEPTHREADATTRINIT=153,      // Unable to initialize thread attribute (check perror)
     IEPTHREADATTRDESTROY=154,      // Unable to destroy thread attribute (check perror)
+    IEPTHREADNOTRUNNING=155,    // A thread stopped running unexpectedly
     /* Stream errors */
     IECREATESTREAM = 200,   // Unable to create a new stream (check herror/perror)
     IEINITSTREAM = 201,     // Unable to initialize stream (check herror/perror)
diff --git a/src/iperf_client_api.c b/src/iperf_client_api.c
index 7ad4c939b..7af54f7aa 100644
--- a/src/iperf_client_api.c
+++ b/src/iperf_client_api.c
@@ -51,6 +51,10 @@
 #endif /* TCP_CA_NAME_MAX */
 #endif /* HAVE_TCP_CONGESTION */
 
+// variable for number of active threads count (for checking if any failed)
+static volatile int running_threads = 0;
+static pthread_mutex_t running_mutex = PTHREAD_MUTEX_INITIALIZER;
+
 void *
 iperf_client_worker_run(void *s) {
     struct iperf_stream *sp = (struct iperf_stream *) s;
@@ -75,6 +79,12 @@ iperf_client_worker_run(void *s) {
     return NULL;
 
   cleanup_and_fail:
+    if (test->debug_level >= DEBUG_LEVEL_INFO) {
+        iperf_printf(sp->test, "Thread number %d FD %d terminated unexpectedly\n", sp->thread_number, sp->socket);
+    }
+    pthread_mutex_lock(&running_mutex);
+    running_threads--;  // Indicate that the thread failed
+    pthread_mutex_unlock(&running_mutex);
     return NULL;
 }
 
@@ -545,6 +555,7 @@ iperf_run_client(struct iperf_test * test)
     int64_t timeout_us;
     int64_t rcv_timeout_us;
     int i_errno_save;
+    int total_num_streams = 0;
 
     if (NULL == test)
     {
@@ -678,13 +689,23 @@ iperf_run_client(struct iperf_test * test)
                     goto cleanup_and_fail;
                 }
 
+                pthread_mutex_lock(&running_mutex);
+                running_threads = 0;
+                total_num_streams = 0;
+                pthread_mutex_unlock(&running_mutex);
                 SLIST_FOREACH(sp, &test->streams, streams) {
+                    pthread_mutex_lock(&running_mutex);
+                    running_threads++; // Count running threads
+                    sp->thread_number = running_threads;
+                    pthread_mutex_unlock(&running_mutex);
+                    total_num_streams++;
+
                     if (pthread_create(&(sp->thr), &attr, &iperf_client_worker_run, sp) != 0) {
                         i_errno = IEPTHREADCREATE;
                         goto cleanup_and_fail;
                     }
                     if (test->debug_level >= DEBUG_LEVEL_INFO) {
-                        iperf_printf(test, "Thread FD %d created\n", sp->socket);
+                        iperf_printf(test, "Thread number %d using FD %d created\n", sp->thread_number, sp->socket);
                     }
                 }
                 if (test->debug_level >= DEBUG_LEVEL_INFO) {
@@ -725,18 +746,18 @@ iperf_run_client(struct iperf_test * test)
                         if (rc != 0 && rc != ESRCH) {
                             i_errno = IEPTHREADCANCEL;
                             errno = rc;
-                            iperf_err(test, "sender cancel in pthread_cancel - %s", iperf_strerror(i_errno));
+                            iperf_err(test, "sender cancel in pthread_cancel of thread %d - %s", sp->thread_number, iperf_strerror(i_errno));
                             goto cleanup_and_fail;
                         }
                         rc = pthread_join(sp->thr, NULL);
                         if (rc != 0 && rc != ESRCH) {
                             i_errno = IEPTHREADJOIN;
                             errno = rc;
-                            iperf_err(test, "sender cancel in pthread_join - %s", iperf_strerror(i_errno));
+                            iperf_err(test, "sender cancel in pthread_join of thread %d - %s", sp->thread_number, iperf_strerror(i_errno));
                             goto cleanup_and_fail;
                         }
                         if (test->debug_level >= DEBUG_LEVEL_INFO) {
-                            iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+                            iperf_printf(test, "Thread number %d FD %d stopped\n", sp->thread_number, sp->socket);
                         }
                     }
                 }
@@ -751,6 +772,14 @@ iperf_run_client(struct iperf_test * test)
 		if (iperf_set_send_state(test, TEST_END) != 0)
                     goto cleanup_and_fail;
 	    }
+
+            /* Terminate if one of the threads failed */
+            if (running_threads != total_num_streams) {
+                i_errno = IEPTHREADNOTRUNNING;
+                iperf_err(test, "Number of running threads is %d but expected %d", running_threads, test->num_streams);
+                goto cleanup_and_fail;
+            }
+
 	}
     }
 
@@ -763,18 +792,18 @@ iperf_run_client(struct iperf_test * test)
             if (rc != 0 && rc != ESRCH) {
                 i_errno = IEPTHREADCANCEL;
                 errno = rc;
-                iperf_err(test, "receiver cancel in pthread_cancel - %s", iperf_strerror(i_errno));
+                iperf_err(test, "receiver cancel in pthread_cancel of thread %d - %s", sp->thread_number, iperf_strerror(i_errno));
                 goto cleanup_and_fail;
             }
             rc = pthread_join(sp->thr, NULL);
             if (rc != 0 && rc != ESRCH) {
                 i_errno = IEPTHREADJOIN;
                 errno = rc;
-                iperf_err(test, "receiver cancel in pthread_join - %s", iperf_strerror(i_errno));
+                iperf_err(test, "receiver cancel in pthread_join of thread %d - %s", sp->thread_number, iperf_strerror(i_errno));
                 goto cleanup_and_fail;
             }
             if (test->debug_level >= DEBUG_LEVEL_INFO) {
-                iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+                iperf_printf(test, "Thread number %d FD %d stopped\n", sp->thread_number, sp->socket);
             }
         }
     }
@@ -804,16 +833,16 @@ iperf_run_client(struct iperf_test * test)
         if (rc != 0 && rc != ESRCH) {
             i_errno = IEPTHREADCANCEL;
             errno = rc;
-            iperf_err(test, "cleanup_and_fail in pthread_cancel - %s", iperf_strerror(i_errno));
+            iperf_err(test, "cleanup_and_fail in pthread_cancel of thread %d - %s", sp->thread_number, iperf_strerror(i_errno));
         }
         rc = pthread_join(sp->thr, NULL); 
         if (rc != 0 && rc != ESRCH) {
             i_errno = IEPTHREADJOIN;
             errno = rc;
-            iperf_err(test, "cleanup_and_fail in pthread_join - %s", iperf_strerror(i_errno));
+            iperf_err(test, "cleanup_and_fail in pthread_join of thread %d - %s", sp->thread_number, iperf_strerror(i_errno));
         }
         if (test->debug_level >= DEBUG_LEVEL_INFO) {
-            iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+            iperf_printf(test, "Thread number %d FD %d stopped\n", sp->thread_number, sp->socket);
         }
     }
     if (test->debug_level >= DEBUG_LEVEL_INFO) {
diff --git a/src/iperf_error.c b/src/iperf_error.c
index 6426554cf..e93f68e60 100644
--- a/src/iperf_error.c
+++ b/src/iperf_error.c
@@ -507,6 +507,10 @@ iperf_strerror(int int_errno)
             snprintf(errstr, len, "unable to destroy thread attributes");
             perr = 1;
             break;
+	case IEPTHREADNOTRUNNING:
+            snprintf(errstr, len, "a thread stopped running unexpectedly");
+            perr = 1;
+            break;
 	default:
 	    snprintf(errstr, len, "int_errno=%d", int_errno);
 	    perr = 1;
diff --git a/src/iperf_server_api.c b/src/iperf_server_api.c
index 77e9c355c..1a88bae81 100644
--- a/src/iperf_server_api.c
+++ b/src/iperf_server_api.c
@@ -66,6 +66,10 @@
 #endif /* TCP_CA_NAME_MAX */
 #endif /* HAVE_TCP_CONGESTION */
 
+// variable for number of active threads count
+static volatile int running_threads = 0;
+static pthread_mutex_t running_mutex = PTHREAD_MUTEX_INITIALIZER;
+
 void *
 iperf_server_worker_run(void *s) {
     struct iperf_stream *sp = (struct iperf_stream *) s;
@@ -90,6 +94,12 @@ iperf_server_worker_run(void *s) {
     return NULL;
 
   cleanup_and_fail:
+    if (test->debug_level >= DEBUG_LEVEL_INFO) {
+        iperf_printf(sp->test, "Thread number %d FD %d terminated unexpectedly\n", sp->thread_number, sp->socket);
+    }
+    pthread_mutex_lock(&running_mutex);
+    running_threads--;  // Indicate that the thread failed
+    pthread_mutex_unlock(&running_mutex);
     return NULL;
 }
 
@@ -424,16 +434,16 @@ cleanup_server(struct iperf_test *test)
         if (rc != 0 && rc != ESRCH) {
             i_errno = IEPTHREADCANCEL;
             errno = rc;
-            iperf_err(test, "cleanup_server in pthread_cancel - %s", iperf_strerror(i_errno));
+            iperf_err(test, "cleanup_server in pthread_cancel of thread %d - %s", sp->thread_number, iperf_strerror(i_errno));
         }
         rc = pthread_join(sp->thr, NULL);
         if (rc != 0 && rc != ESRCH) {
             i_errno = IEPTHREADJOIN;
             errno = rc;
-            iperf_err(test, "cleanup_server in pthread_join - %s", iperf_strerror(i_errno));
+            iperf_err(test, "cleanup_server in pthread_join of thread %d - %s", sp->thread_number, iperf_strerror(i_errno));
         }
         if (test->debug_level >= DEBUG_LEVEL_INFO) {
-            iperf_printf(test, "Thread FD %d stopped\n", sp->socket);
+            iperf_printf(test, "Thread number %d FD %d stopped\n", sp->thread_number, sp->socket);
         }
     }
     i_errno = i_errno_save;
@@ -511,6 +521,7 @@ iperf_run_server(struct iperf_test *test)
     int64_t t_usecs;
     int64_t timeout_us;
     int64_t rcv_timeout_us;
+    int total_num_streams = 0;
 
     if (test->logfile)
         if (iperf_open_logfile(test) < 0)
@@ -872,14 +883,24 @@ iperf_run_server(struct iperf_test *test)
                         cleanup_server(test);
                     };
 
+                    pthread_mutex_lock(&running_mutex);
+                    running_threads = 0;
+                    total_num_streams = 0;
+                    pthread_mutex_unlock(&running_mutex);
                     SLIST_FOREACH(sp, &test->streams, streams) {
+                        pthread_mutex_lock(&running_mutex);
+                        running_threads++; // Count running threads
+                        sp->thread_number = running_threads;
+                        pthread_mutex_unlock(&running_mutex);
+                        total_num_streams++;
+
                         if (pthread_create(&(sp->thr), &attr, &iperf_server_worker_run, sp) != 0) {
                             i_errno = IEPTHREADCREATE;
                             cleanup_server(test);
                             return -1;
                         }
                         if (test->debug_level >= DEBUG_LEVEL_INFO) {
-                            iperf_printf(test, "Thread FD %d created\n", sp->socket);
+                            iperf_printf(test, "Thread number %d FD %d created\n", sp->thread_number, sp->socket);
                         }
                     }
                     if (test->debug_level >= DEBUG_LEVEL_INFO) {
@@ -893,6 +914,15 @@ iperf_run_server(struct iperf_test *test)
             }
         }
 
+        /* Terminate if any thread failed */
+        if (test->state == TEST_RUNNING) {
+            if (running_threads != total_num_streams) {
+                i_errno = IEPTHREADNOTRUNNING;
+                iperf_err(test, "Number of running threads is %d but expected %d", running_threads, test->num_streams);
+                cleanup_server(test);
+            }
+        }
+
 	if (result == 0 ||
 	    (timeout != NULL && timeout->tv_sec == 0 && timeout->tv_usec == 0)) {
 	    /* Run the timers. */