--- a/net/minecraft/server/commands/DefaultGameModeCommands.java
+++ b/net/minecraft/server/commands/DefaultGameModeCommands.java
@@ -25,9 +25,13 @@
         GameType gameType = minecraftServer.getForcedGameType();
         if (gameType != null) {
             for(ServerPlayer serverPlayer : minecraftServer.getPlayerList().getPlayers()) {
-                if (serverPlayer.setGameMode(gameType)) {
-                    ++i;
+                // Paper start - extend PlayerGameModeChangeEvent
+                org.bukkit.event.player.PlayerGameModeChangeEvent event = serverPlayer.setGameMode(gameType, org.bukkit.event.player.PlayerGameModeChangeEvent.Cause.DEFAULT_GAMEMODE, net.kyori.adventure.text.Component.empty());
+                if (event != null && event.isCancelled()) {
+                    source.sendSuccess(() -> io.papermc.paper.adventure.PaperAdventure.asVanilla(event.cancelMessage()), false);
                 }
+                // Paper end
+                    ++i;
             }
         }
 
