diff --git a/core/java/src/net/i2p/data/i2cp/SessionStatusMessage.java b/core/java/src/net/i2p/data/i2cp/SessionStatusMessage.java
index ea135f792..d01acdf4f 100644
--- a/core/java/src/net/i2p/data/i2cp/SessionStatusMessage.java
+++ b/core/java/src/net/i2p/data/i2cp/SessionStatusMessage.java
@@ -34,6 +34,11 @@ public class SessionStatusMessage extends I2CPMessageImpl {
     public final static int STATUS_INVALID = 3;
     /** @since 0.9.12 */
     public final static int STATUS_REFUSED = 4;
+    /**
+     *  Used internally, not in spec, will be remapped to STATUS_INVALID before being sent.
+     *  @since 0.9.44
+     */
+    public final static int STATUS_DUP_DEST = 5;
 
     public SessionStatusMessage() {
         setStatus(STATUS_INVALID);
diff --git a/router/java/src/net/i2p/router/client/ClientConnectionRunner.java b/router/java/src/net/i2p/router/client/ClientConnectionRunner.java
index ac930391a..32a17568c 100644
--- a/router/java/src/net/i2p/router/client/ClientConnectionRunner.java
+++ b/router/java/src/net/i2p/router/client/ClientConnectionRunner.java
@@ -552,7 +552,7 @@ class ClientConnectionRunner {
         sp.config = config;
         SessionParams old = _sessions.putIfAbsent(destHash, sp);
         if (old != null)
-            return SessionStatusMessage.STATUS_INVALID;
+            return SessionStatusMessage.STATUS_DUP_DEST;
         // We process a few options here, but most are handled by the tunnel manager.
         // The ones here can't be changed later.
         Properties opts = config.getOptions();
diff --git a/router/java/src/net/i2p/router/client/ClientManager.java b/router/java/src/net/i2p/router/client/ClientManager.java
index 07f234f1d..df2eee976 100644
--- a/router/java/src/net/i2p/router/client/ClientManager.java
+++ b/router/java/src/net/i2p/router/client/ClientManager.java
@@ -325,7 +325,7 @@ class ClientManager {
         synchronized (_runners) {
             boolean fail = _runnersByHash.containsKey(dest.calculateHash());
             if (fail) {
-                rv = SessionStatusMessage.STATUS_INVALID;
+                rv = SessionStatusMessage.STATUS_DUP_DEST;
             } else {
                 SessionId id = locked_getNextSessionId();
                 if (id != null) {
@@ -339,7 +339,7 @@ class ClientManager {
                 }
             }
         }
-        if (rv == SessionStatusMessage.STATUS_INVALID) {
+        if (rv == SessionStatusMessage.STATUS_DUP_DEST) {
             _log.log(Log.CRIT, "Client attempted to register duplicate destination " + dest.toBase32());
         } else if (rv == SessionStatusMessage.STATUS_REFUSED) {
             _log.error("Max sessions exceeded " + dest.toBase32());
diff --git a/router/java/src/net/i2p/router/client/ClientMessageEventListener.java b/router/java/src/net/i2p/router/client/ClientMessageEventListener.java
index b44a3a42a..344f9d310 100644
--- a/router/java/src/net/i2p/router/client/ClientMessageEventListener.java
+++ b/router/java/src/net/i2p/router/client/ClientMessageEventListener.java
@@ -326,12 +326,17 @@ class ClientMessageEventListener implements I2CPMessageReader.I2CPMessageEventLi
             if (_log.shouldLog(Log.ERROR))
                 _log.error("Session establish failed: code = " + status);
             String msg;
-            if (status == SessionStatusMessage.STATUS_INVALID)
+            if (status == SessionStatusMessage.STATUS_DUP_DEST) {
                 msg = "duplicate destination";
-            else if (status == SessionStatusMessage.STATUS_REFUSED)
+                // not in spec, change to INVALID if we send it
+                // status = SessionStatusMessage.STATUS_INVALID
+            } else if (status == SessionStatusMessage.STATUS_INVALID) {
+                msg = "bad session configuration parameters";
+            } else if (status == SessionStatusMessage.STATUS_REFUSED) {
                 msg = "session limit exceeded";
-            else
+            } else {
                 msg = "unknown error";
+            }
             _runner.disconnectClient(msg);
             return;
         }