diff --git a/src/title_screen/title_screen.gd b/src/title_screen/title_screen.gd
index 142613c..9515c39 100644
--- a/src/title_screen/title_screen.gd
+++ b/src/title_screen/title_screen.gd
@@ -38,6 +38,9 @@ const RANDOM_NAMES = [
 @onready var hostname_input: LineEdit = %HostnameInput
 @onready var join_port_input: SpinBox = %JoinPortInput
 
+@onready var err_already_in_use: ColorRect = %ErrAlreadyInUse
+@onready var err_cant_create: ColorRect = %ErrCantCreate
+
 
 func _ready() -> void:
 	name_input.text = RANDOM_NAMES.pick_random()
@@ -73,19 +76,34 @@ func _build_game() -> Game:
 	return game
 
 
+func _peer_ok(err: Error) -> bool:
+	match err:
+		ERR_ALREADY_IN_USE:
+			err_already_in_use.show()
+			return false
+		ERR_CANT_CREATE:
+			err_cant_create.show()
+			return false
+	return true
+
+
 func start_host_lobby() -> void:
-	var game: Game = _build_game()
 	var peer := ENetMultiplayerPeer.new()
-	peer.create_server(host_port_input.value, MAX_CLIENTS)
+	if not _peer_ok(peer.create_server(int(host_port_input.value), MAX_CLIENTS)):
+		return
+
+	var game: Game = _build_game()
 	add_sibling(game)
 	game.multiplayer.multiplayer_peer = peer
 	queue_free()
 
 
 func join_lobby() -> void:
-	var game: Game = _build_game()
 	var peer := ENetMultiplayerPeer.new()
-	peer.create_client(hostname_input.text, join_port_input.value)
+	if not _peer_ok(peer.create_client(hostname_input.text, int(join_port_input.value))):
+		return
+
+	var game: Game = _build_game()
 	add_sibling(game)
 	game.multiplayer.multiplayer_peer = peer
 	queue_free()
diff --git a/src/title_screen/title_screen.tscn b/src/title_screen/title_screen.tscn
index c62a9ff..98622be 100644
--- a/src/title_screen/title_screen.tscn
+++ b/src/title_screen/title_screen.tscn
@@ -165,6 +165,104 @@ layout_mode = 2
 text = "Cancel
 "
 
+[node name="ErrAlreadyInUse" type="ColorRect" parent="."]
+unique_name_in_owner = true
+visible = false
+layout_mode = 1
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+color = Color(0, 0, 0, 0.156863)
+
+[node name="PanelContainer" type="PanelContainer" parent="ErrAlreadyInUse"]
+layout_mode = 1
+anchors_preset = 8
+anchor_left = 0.5
+anchor_top = 0.5
+anchor_right = 0.5
+anchor_bottom = 0.5
+offset_left = -20.0
+offset_top = -20.0
+offset_right = 20.0
+offset_bottom = 20.0
+grow_horizontal = 2
+grow_vertical = 2
+
+[node name="MarginContainer" type="MarginContainer" parent="ErrAlreadyInUse/PanelContainer"]
+layout_mode = 2
+theme_override_constants/margin_left = 32
+theme_override_constants/margin_top = 16
+theme_override_constants/margin_right = 32
+theme_override_constants/margin_bottom = 16
+
+[node name="VBoxContainer" type="VBoxContainer" parent="ErrAlreadyInUse/PanelContainer/MarginContainer"]
+layout_mode = 2
+theme_override_constants/separation = 16
+
+[node name="Label" type="Label" parent="ErrAlreadyInUse/PanelContainer/MarginContainer/VBoxContainer"]
+layout_mode = 2
+theme_override_colors/font_color = Color(1, 0.3, 0.3, 1)
+theme_override_constants/outline_size = 4
+theme_override_font_sizes/font_size = 24
+text = "ERROR: Connection already in use."
+horizontal_alignment = 1
+
+[node name="Button" type="Button" parent="ErrAlreadyInUse/PanelContainer/MarginContainer/VBoxContainer"]
+layout_mode = 2
+size_flags_horizontal = 4
+text = "OK"
+
+[node name="ErrCantCreate" type="ColorRect" parent="."]
+unique_name_in_owner = true
+visible = false
+layout_mode = 1
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+color = Color(0, 0, 0, 0.156863)
+
+[node name="PanelContainer" type="PanelContainer" parent="ErrCantCreate"]
+layout_mode = 1
+anchors_preset = 8
+anchor_left = 0.5
+anchor_top = 0.5
+anchor_right = 0.5
+anchor_bottom = 0.5
+offset_left = -20.0
+offset_top = -20.0
+offset_right = 20.0
+offset_bottom = 20.0
+grow_horizontal = 2
+grow_vertical = 2
+
+[node name="MarginContainer" type="MarginContainer" parent="ErrCantCreate/PanelContainer"]
+layout_mode = 2
+theme_override_constants/margin_left = 32
+theme_override_constants/margin_top = 16
+theme_override_constants/margin_right = 32
+theme_override_constants/margin_bottom = 16
+
+[node name="VBoxContainer" type="VBoxContainer" parent="ErrCantCreate/PanelContainer/MarginContainer"]
+layout_mode = 2
+theme_override_constants/separation = 16
+
+[node name="Label" type="Label" parent="ErrCantCreate/PanelContainer/MarginContainer/VBoxContainer"]
+layout_mode = 2
+theme_override_colors/font_color = Color(1, 0.3, 0.3, 1)
+theme_override_constants/outline_size = 4
+theme_override_font_sizes/font_size = 24
+text = "ERROR: Can't create connection."
+horizontal_alignment = 1
+
+[node name="Button" type="Button" parent="ErrCantCreate/PanelContainer/MarginContainer/VBoxContainer"]
+layout_mode = 2
+size_flags_horizontal = 4
+text = "OK"
+
 [connection signal="pressed" from="Menu/MainMenu/Host" to="." method="show_host_menu"]
 [connection signal="pressed" from="Menu/MainMenu/Join" to="." method="show_join_menu"]
 [connection signal="pressed" from="Menu/MainMenu/Quit" to="." method="quit"]
@@ -172,3 +270,5 @@ text = "Cancel
 [connection signal="pressed" from="Menu/HostMenu/Cancel" to="." method="show_main_menu"]
 [connection signal="pressed" from="Menu/JoinMenu/Connect" to="." method="join_lobby"]
 [connection signal="pressed" from="Menu/JoinMenu/Cancel" to="." method="show_main_menu"]
+[connection signal="pressed" from="ErrAlreadyInUse/PanelContainer/MarginContainer/VBoxContainer/Button" to="ErrAlreadyInUse" method="hide"]
+[connection signal="pressed" from="ErrCantCreate/PanelContainer/MarginContainer/VBoxContainer/Button" to="ErrCantCreate" method="hide"]
diff --git a/ui.theme b/ui.theme
index 893a361..13b27d2 100644
Binary files a/ui.theme and b/ui.theme differ