Try and make the client not crash when switching teams. @lazertester

api/src/main/java/net/md_5/bungee/api/scoreboard/Team.java

@@ -21,4 +21,14 @@ public class Team
     {
         return Collections.unmodifiableSet( players );
     }
+
+    public void addPlayer(String name)
+    {
+        players.add( name );
+    }
+
+    public void removePlayer(String name)
+    {
+        players.remove( name );
+    }
 }

proxy/src/main/java/net/md_5/bungee/ServerConnector.java

@@ -14,6 +14,7 @@ import net.md_5.bungee.api.event.ServerConnectedEvent;
 import net.md_5.bungee.api.event.ServerKickEvent;
 import net.md_5.bungee.api.scoreboard.Objective;
 import net.md_5.bungee.api.scoreboard.Score;
+import net.md_5.bungee.api.scoreboard.Team;
 import net.md_5.bungee.connection.CancelSendSignal;
 import net.md_5.bungee.connection.DownstreamBridge;
 import net.md_5.bungee.netty.HandlerBoss;
@@ -23,6 +24,7 @@ import net.md_5.bungee.packet.Packet9Respawn;
 import net.md_5.bungee.packet.PacketCDClientStatus;
 import net.md_5.bungee.packet.PacketCEScoreboardObjective;
 import net.md_5.bungee.packet.PacketCFScoreboardScore;
+import net.md_5.bungee.packet.PacketD1Team;
 import net.md_5.bungee.packet.PacketFAPluginMessage;
 import net.md_5.bungee.packet.PacketFDEncryptionRequest;
 import net.md_5.bungee.packet.PacketFFKick;
@@ -122,6 +124,10 @@ public class ServerConnector extends PacketHandler
                     {
                         user.ch.write( new PacketCFScoreboardScore( score.getItemName(), (byte) 1, null, 0 ) );
                     }
+                    for ( Team team : user.serverSentScoreboard.getTeams() )
+                    {
+                        user.ch.write( PacketD1Team.destroy( team.getName() ) );
+                    }
                     user.serverSentScoreboard = null;
                 }
 

proxy/src/main/java/net/md_5/bungee/connection/DownstreamBridge.java

@@ -20,6 +20,7 @@ import net.md_5.bungee.api.scoreboard.Objective;
 import net.md_5.bungee.api.scoreboard.Position;
 import net.md_5.bungee.api.scoreboard.Score;
 import net.md_5.bungee.api.scoreboard.Scoreboard;
+import net.md_5.bungee.api.scoreboard.Team;
 import net.md_5.bungee.packet.Packet0KeepAlive;
 import net.md_5.bungee.packet.Packet3Chat;
 import net.md_5.bungee.packet.Packet9Respawn;
@@ -27,6 +28,7 @@ import net.md_5.bungee.packet.PacketC9PlayerListItem;
 import net.md_5.bungee.packet.PacketCEScoreboardObjective;
 import net.md_5.bungee.packet.PacketCFScoreboardScore;
 import net.md_5.bungee.packet.PacketD0DisplayScoreboard;
+import net.md_5.bungee.packet.PacketD1Team;
 import net.md_5.bungee.packet.PacketFAPluginMessage;
 import net.md_5.bungee.packet.PacketFFKick;
 import net.md_5.bungee.packet.PacketHandler;
@@ -141,6 +143,43 @@ public class DownstreamBridge extends PacketHandler
         con.serverSentScoreboard = new Scoreboard( displayScoreboard.name, Position.values()[displayScoreboard.position] );
     }
 
+    @Override
+    public void handle(PacketD1Team team) throws Exception
+    {
+        if ( con.serverSentScoreboard != null )
+        {
+            // Remove team and move on
+            if ( team.mode == 1 )
+            {
+                con.serverSentScoreboard.removeTeam( team.name );
+                return;
+            }
+
+            // Create or get old team
+            Team t = ( team.mode == 0 ) ? new Team( team.name ) : con.serverSentScoreboard.getTeam( team.name );
+            if ( t != null )
+            {
+                if ( team.mode == 0 || team.mode == 2 )
+                {
+                    t.setDisplayName( team.displayName );
+                    t.setPrefix( team.prefix );
+                    t.setSuffix( team.suffix );
+                    t.setFriendlyMode( team.friendlyFire );
+                }
+                for ( String s : team.players )
+                {
+                    if ( team.mode == 0 || team.mode == 3 )
+                    {
+                        t.addPlayer( s );
+                    } else
+                    {
+                        t.removePlayer( s );
+                    }
+                }
+            }
+        }
+    }
+
     @Override
     public void handle(PacketFAPluginMessage pluginMessage) throws Exception
     {

proxy/src/main/java/net/md_5/bungee/packet/PacketD1Team.java

@@ -42,6 +42,19 @@ public class PacketD1Team extends DefinedPacket
         }
     }
 
+    public PacketD1Team()
+    {
+        super( 0xD1 );
+    }
+
+    public static PacketD1Team destroy(String name)
+    {
+        PacketD1Team packet = new PacketD1Team();
+        packet.writeUTF( name );
+        packet.writeByte( 1 );
+        return packet;
+    }
+
     @Override
     public void handle(PacketHandler handler) throws Exception
     {