diff --git a/src/mod_legacy_auth.erl b/src/mod_legacy_auth.erl
index 722a05738..0ae3253c9 100644
--- a/src/mod_legacy_auth.erl
+++ b/src/mod_legacy_auth.erl
@@ -61,11 +61,16 @@ mod_opt_type(_) ->
       c2s_state() | {stop, c2s_state()}.
 c2s_unauthenticated_packet(State, #iq{type = T, sub_els = [_]} = IQ)
   when T == get; T == set ->
-    case xmpp:get_subtag(IQ, #legacy_auth{}) of
+    try xmpp:try_subtag(IQ, #legacy_auth{}) of
 	#legacy_auth{} = Auth ->
 	    {stop, authenticate(State, xmpp:set_els(IQ, [Auth]))};
 	false ->
 	    State
+    catch _:{xmpp_codec, Why} ->
+	    Txt = xmpp:io_format_error(Why),
+	    Lang = maps:get(lang, State),
+	    Err = xmpp:make_error(IQ, xmpp:error_bad_request(Txt, Lang)),
+	    {stop, ejabberd_c2s:send(State, Err)}
     end;
 c2s_unauthenticated_packet(State, _) ->
     State.
diff --git a/src/mod_muc_room.erl b/src/mod_muc_room.erl
index 271e49b45..e8d61dacb 100644
--- a/src/mod_muc_room.erl
+++ b/src/mod_muc_room.erl
@@ -4006,7 +4006,7 @@ route_invitation(From, Invitation, Lang, StateData) ->
 %% Otherwise, an error message is sent to the sender.
 -spec handle_roommessage_from_nonparticipant(message(), state(), jid()) -> ok.
 handle_roommessage_from_nonparticipant(Packet, StateData, From) ->
-    case xmpp:get_subtag(Packet, #muc_user{}) of
+    try xmpp:try_subtag(Packet, #muc_user{}) of
 	#muc_user{decline = #muc_decline{to = #jid{} = To} = Decline} = XUser ->
 	    NewDecline = Decline#muc_decline{to = undefined, from = From},
 	    NewXUser = XUser#muc_user{decline = NewDecline},
@@ -4018,6 +4018,10 @@ handle_roommessage_from_nonparticipant(Packet, StateData, From) ->
 			"to the conference">>,
 	    Err = xmpp:err_not_acceptable(ErrText, xmpp:get_lang(Packet)),
 	    ejabberd_router:route_error(Packet, Err)
+    catch _:{xmpp_codec, Why} ->
+	    Txt = xmpp:io_format_error(Why),
+	    Err = xmpp:err_bad_request(Txt, xmpp:get_lang(Packet)),
+	    ejabberd_router:route_error(Packet, Err)
     end.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
diff --git a/src/mod_multicast.erl b/src/mod_multicast.erl
index 7b772521d..fa9e19aef 100644
--- a/src/mod_multicast.erl
+++ b/src/mod_multicast.erl
@@ -402,7 +402,7 @@ strip_addresses_element(Packet) ->
 	#addresses{list = Addrs} ->
 	    PacketStripped = xmpp:remove_subtag(Packet, #addresses{}),
 	    {ok, PacketStripped, Addrs};
-	undefined ->
+	false ->
 	    throw(eadsele)
     end.
 
diff --git a/src/mod_privilege.erl b/src/mod_privilege.erl
index dab7a619b..def097739 100644
--- a/src/mod_privilege.erl
+++ b/src/mod_privilege.erl
@@ -274,7 +274,7 @@ get_permissions(ServerHost) ->
 forward_message(#message{to = To} = Msg) ->
     ServerHost = To#jid.lserver,
     Lang = xmpp:get_lang(Msg),
-    case xmpp:get_subtag(Msg, #privilege{}) of
+    try xmpp:try_subtag(Msg, #privilege{}) of
 	#privilege{forwarded = #forwarded{xml_els = [SubEl]}} ->
 	    try xmpp:decode(SubEl, ?NS_CLIENT, [ignore_els]) of
 		#message{} = NewMsg ->
@@ -297,7 +297,11 @@ forward_message(#message{to = To} = Msg) ->
 		    ejabberd_router:route_error(Msg, Err)
 	    end;
 	_ ->
-	    Txt = <<"Invalid <forwarded/> element">>,
+	    Txt = <<"No <forwarded/> element found">>,
+	    Err = xmpp:err_bad_request(Txt, Lang),
+	    ejabberd_router:route_error(Msg, Err)
+    catch _:{xmpp_codec, Why} ->
+	    Txt = xmpp:io_format_error(Why),
 	    Err = xmpp:err_bad_request(Txt, Lang),
 	    ejabberd_router:route_error(Msg, Err)
     end.
diff --git a/src/mod_register.erl b/src/mod_register.erl
index 77557ee0b..c74d99d38 100644
--- a/src/mod_register.erl
+++ b/src/mod_register.erl
@@ -95,7 +95,7 @@ stream_feature_register(Acc, Host) ->
 c2s_unauthenticated_packet(#{ip := IP, server := Server} = State,
 			   #iq{type = T, sub_els = [_]} = IQ)
   when T == set; T == get ->
-    case xmpp:get_subtag(IQ, #register{}) of
+    try xmpp:try_subtag(IQ, #register{}) of
 	#register{} = Register ->
 	    {Address, _} = IP,
 	    IQ1 = xmpp:set_els(IQ, [Register]),
@@ -105,6 +105,11 @@ c2s_unauthenticated_packet(#{ip := IP, server := Server} = State,
 	    {stop, ejabberd_c2s:send(State, ResIQ1)};
 	false ->
 	    State
+    catch _:{xmpp_codec, Why} ->
+	    Txt = xmpp:io_format_error(Why),
+	    Lang = maps:get(lang, State),
+	    Err = xmpp:make_error(IQ, xmpp:error_bad_request(Txt, Lang)),
+	    {stop, ejabberd_c2s:send(State, Err)}
     end;
 c2s_unauthenticated_packet(State, _) ->
     State.