diff --git a/asyncmsg/Error.h b/asyncmsg/Error.h
index 35af88e9d596927a9796e4e724b3bfb82388dc7f..888d3fff39f8b7780a112eabc34361700db45989 100644
--- a/asyncmsg/Error.h
+++ b/asyncmsg/Error.h
@@ -11,7 +11,7 @@ namespace asyncmsg
 enum class Error:
     int
 {
-  SESSION_CLOSED,
+  SESSION_NOT_OPEN,
   SESSION_NOT_CLOSED,
   RESERVED_MESSAGE_TYPE,
   UNEXPECTED_MESSAGE_TYPE,
diff --git a/src/Error.cxx b/src/Error.cxx
index 0ef77f1a7343f71613adc4153e2e89e005bb5af5..be70f3509cdd73ff9d1d2282f237b60c5fca0850 100644
--- a/src/Error.cxx
+++ b/src/Error.cxx
@@ -19,8 +19,8 @@ ErrorCategory ErrorCategory::s_instance;
 
 std::string ErrorCategory::message(int value) const
 {
-  if (value == static_cast<int>(Error::SESSION_CLOSED)) {
-    return "The session is closed";
+  if (value == static_cast<int>(Error::SESSION_NOT_OPEN)) {
+    return "The session is not open";
   }
   if (value == static_cast<int>(Error::SESSION_NOT_CLOSED)) {
     return "The session is not closed";
diff --git a/src/Session.cxx b/src/Session.cxx
index 234b5d740c565047fae25557589daebc31ae4fa7..a44ac83525d43811784e4c6663112f6944b1a0ba 100644
--- a/src/Session.cxx
+++ b/src/Session.cxx
@@ -137,7 +137,7 @@ void Session::asyncClose()
           // use post to avoid stack overflows if the user calls asyncClose again from onCloseError()
           m_strand.post(
               [this, self] () {
-                onCloseError(Error::SESSION_CLOSED);
+                onCloseError(Error::SESSION_NOT_OPEN);
               });
         }
         else {
@@ -169,7 +169,7 @@ void Session::asyncReceive()
           // onReceiveError()
           m_strand.post(
               [this, self] () {
-                onReceiveError(Error::SESSION_CLOSED, std::unique_ptr<InputMessage>());
+                onReceiveError(Error::SESSION_NOT_OPEN, std::unique_ptr<InputMessage>());
               });
         }
         else {
@@ -251,7 +251,7 @@ void Session::asyncSend(std::unique_ptr<const OutputMessage> message)
           // use post to avoid stack overflows if the user calls asyncSend again from onSendError()
           m_strand.post(
               [this, self, bareMessage] () {
-                onSendError(Error::SESSION_CLOSED, std::unique_ptr<const OutputMessage>(bareMessage));
+                onSendError(Error::SESSION_NOT_OPEN, std::unique_ptr<const OutputMessage>(bareMessage));
               });
         }
         else if (bareMessage->typeId() >= RESERVED_MESSAGE_TYPES_BASE) {
diff --git a/src/UDPSession.cxx b/src/UDPSession.cxx
index 2b6d372eb5bb651effc45a95ad64cadb94570a7c..b47dc80d117cc70c22b5bbcac1ecaf4f7b578afe 100644
--- a/src/UDPSession.cxx
+++ b/src/UDPSession.cxx
@@ -57,7 +57,7 @@ void UDPSession::asyncReceive()
           // onReceiveError()
           m_strand.post(
               [this, self] () {
-                onReceiveError(Error::SESSION_CLOSED, std::unique_ptr<InputMessage>());
+                onReceiveError(Error::SESSION_NOT_OPEN, std::unique_ptr<InputMessage>());
               });
         }
         else {
@@ -129,7 +129,7 @@ void UDPSession::asyncSend(std::unique_ptr<const OutputMessage> message)
           // use post to avoid stack overflows if the user calls asyncSend again from onSendError()
           m_strand.post(
               [this, self, bareMessage] () {
-                onSendError(Error::SESSION_CLOSED, std::unique_ptr<const OutputMessage>(bareMessage));
+                onSendError(Error::SESSION_NOT_OPEN, std::unique_ptr<const OutputMessage>(bareMessage));
               });
         }
         else if (bareMessage->typeId() >= RESERVED_MESSAGE_TYPES_BASE) {