Display thrown exception upon starting debug session in error dialog.

main.py

@@ -271,11 +271,14 @@ def run(self, launch_browser=False, restart=False):
         threading.Thread(target=self.listen).start()
 
     def listen(self):
-        # Start listening for response from debugger engine
-        S.SESSION.listen()
-        # On connect run method which handles connection
-        if S.SESSION and S.SESSION.connected:
-            sublime.set_timeout(self.connected, 0)
+        try:
+            # Start listening for response from debugger engine
+            S.SESSION.listen()
+            # On connect run method which handles connection
+            if S.SESSION and S.SESSION.connected:
+                sublime.set_timeout(self.connected, 0)
+        except (protocol.ProtocolListenException) as e:
+            sublime.error_message('Unable to start Xdebug debugging session.\n\n%s' % e)
 
     def connected(self):
         sublime.set_timeout(lambda: sublime.status_message('Xdebug: Connected'), 100)

xdebug/protocol.py

@@ -248,7 +248,7 @@ def listen(self):
                 self.socket = None
             except:
                 e = sys.exc_info()[1]
-                raise ProtocolConnectionException(e)
+                raise ProtocolListenException(e)
 
             # Accept incoming connection on configured port
             while self.listening:
@@ -276,7 +276,7 @@ def listen(self):
             # Return socket connection
             return self.socket
         else:
-            raise ProtocolConnectionException('Could not create socket server.')
+            raise ProtocolListenException('Could not create socket server.')
 
 
 class ProtocolException(Exception):
@@ -285,3 +285,7 @@ class ProtocolException(Exception):
 
 class ProtocolConnectionException(ProtocolException):
     pass
+
+
+class ProtocolListenException(ProtocolException):
+    pass