diff --git a/src/os/unix/ngx_channel.c b/src/os/unix/ngx_channel.c
index 1efa0667c..b03bbbb15 100644
--- a/src/os/unix/ngx_channel.c
+++ b/src/os/unix/ngx_channel.c
@@ -134,6 +134,13 @@ ngx_read_channel(ngx_socket_t s, ngx_channel_t *ch, size_t size, ngx_log_t *log)
         }
 
         ngx_log_error(NGX_LOG_ALERT, log, err, "recvmsg() failed");
+
+        if (err == NGX_EMSGSIZE || err == NGX_EMFILE) {
+            /* file descriptor table is full */
+            ngx_memzero(ch, size);
+            return 0;
+        }
+
         return NGX_ERROR;
     }
 
@@ -152,27 +159,29 @@ ngx_read_channel(ngx_socket_t s, ngx_channel_t *ch, size_t size, ngx_log_t *log)
 
     if (ch->command == NGX_CMD_OPEN_CHANNEL) {
 
-        if (cmsg.cm.cmsg_len < (socklen_t) CMSG_LEN(sizeof(int))) {
+        if (msg.msg_controllen < (socklen_t) CMSG_LEN(sizeof(int))) {
             ngx_log_error(NGX_LOG_ALERT, log, 0,
                           "recvmsg() returned too small ancillary data");
-            return NGX_ERROR;
-        }
+            ch->fd = -1;
 
-        if (cmsg.cm.cmsg_level != SOL_SOCKET || cmsg.cm.cmsg_type != SCM_RIGHTS)
+        } else if (cmsg.cm.cmsg_level != SOL_SOCKET
+                   || cmsg.cm.cmsg_type != SCM_RIGHTS)
         {
             ngx_log_error(NGX_LOG_ALERT, log, 0,
                           "recvmsg() returned invalid ancillary data "
                           "level %d or type %d",
                           cmsg.cm.cmsg_level, cmsg.cm.cmsg_type);
             return NGX_ERROR;
+
+        } else {
+
+            /* ch->fd = *(int *) CMSG_DATA(&cmsg.cm); */
+
+            ngx_memcpy(&ch->fd, CMSG_DATA(&cmsg.cm), sizeof(int));
         }
-
-        /* ch->fd = *(int *) CMSG_DATA(&cmsg.cm); */
-
-        ngx_memcpy(&ch->fd, CMSG_DATA(&cmsg.cm), sizeof(int));
     }
 
-    if (msg.msg_flags & (MSG_TRUNC|MSG_CTRUNC)) {
+    if (msg.msg_flags & MSG_TRUNC) {
         ngx_log_error(NGX_LOG_ALERT, log, 0,
                       "recvmsg() truncated data");
     }
@@ -183,10 +192,11 @@ ngx_read_channel(ngx_socket_t s, ngx_channel_t *ch, size_t size, ngx_log_t *log)
         if (msg.msg_accrightslen != sizeof(int)) {
             ngx_log_error(NGX_LOG_ALERT, log, 0,
                           "recvmsg() returned no ancillary data");
-            return NGX_ERROR;
-        }
+            ch->fd = -1;
 
-        ch->fd = fd;
+        } else {
+            ch->fd = fd;
+        }
     }
 
 #endif
diff --git a/src/os/unix/ngx_process_cycle.c b/src/os/unix/ngx_process_cycle.c
index 5bc5ce979..33c25487b 100644
--- a/src/os/unix/ngx_process_cycle.c
+++ b/src/os/unix/ngx_process_cycle.c
@@ -1073,6 +1073,12 @@ ngx_channel_handler(ngx_event_t *ev)
                            ch.slot, ch.pid, ngx_processes[ch.slot].pid,
                            ngx_processes[ch.slot].channel[0]);
 
+            if (ngx_processes[ch.slot].channel[0] == -1
+                || ngx_processes[ch.slot].pid != ch.pid)
+            {
+                break;
+            }
+
             if (close(ngx_processes[ch.slot].channel[0]) == -1) {
                 ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_errno,
                               "close() channel failed");