diff --git a/chat/locales/en-US/irc.properties b/chat/locales/en-US/irc.properties
index f39f83aab7..c95f5e5c1f 100644
--- a/chat/locales/en-US/irc.properties
+++ b/chat/locales/en-US/irc.properties
@@ -109,7 +109,7 @@ message.parted=%1$S has left the room (Part%2$S).
 message.parted.reason=: %S
 #    %1$S is the user's nick, %2$S is message.quit2 if a quit message is given.
 message.quit=%1$S has left the room (Quit%2$S).
-#    The paramter is the quit message given by the user.
+#    The parameter is the quit message given by the user.
 message.quit2=: %S
 #    %1$S is the nickname of the user that invited us, %2$S is the conversation
 #    name.
@@ -161,8 +161,12 @@ error.mode.wrongUser=You cannot change modes for other users.
 error.noSuchNick=%S is not online.
 error.wasNoSuchNick=There was no nickname: %S
 error.noSuchChannel=There is no channel: %S.
+error.unavailable=%S is temporarily unavailable.
 #    %S is the channel name.
+error.channelBanned=You have been banned from %S.
 error.cannotSendToChannel=You cannot send messages to %S.
+error.channelFull=The channel %S is full.
+error.inviteOnly=You must be invited to join %S.
 error.nonUniqueTarget=%S is not a unique user@host or shortname or you have tried to join too many channels at once.
 error.notChannelOp=You are not a channel operator on %S.
 error.notChannelOwner=You are not a channel owner of %S.
diff --git a/chat/protocols/irc/irc.js b/chat/protocols/irc/irc.js
index 2ed51c0f36..ffec2bed3a 100644
--- a/chat/protocols/irc/irc.js
+++ b/chat/protocols/irc/irc.js
@@ -795,7 +795,6 @@ function ircAccount(aProtocol, aImAccount) {
   this.trackQueue = [];
   this.pendingIsOnQueue = [];
   this.whoisInformation = new NormalizedMap(this.normalizeNick.bind(this));
-  this._chatRoomFieldsList = {};
   this._caps = [];
 
   this._roomInfoCallbacks = new Set();
@@ -1428,10 +1427,6 @@ ircAccount.prototype = {
 
   createConversation: function(aName) this.getConversation(aName),
 
-  // Temporarily stores the prplIChatRoomFieldValues passed to joinChat for
-  // each channel to enable later reconnections.
-  _chatRoomFieldsList: {},
-
   // aComponents implements prplIChatRoomFieldValues.
   joinChat: function(aComponents) {
     let channel = aComponents.getValue("channel");
@@ -1439,6 +1434,7 @@ ircAccount.prototype = {
       this.ERROR("joinChat called without a channel name.");
       return null;
     }
+
     // A channel prefix is required. If the user didn't include one,
     // we prepend # automatically to match the behavior of other
     // clients. Not doing it used to cause user confusion.
@@ -1457,13 +1453,13 @@ ircAccount.prototype = {
     if (key)
       params.push(key);
     let defaultName = key ? channel + " " + key : channel;
-    this._chatRoomFieldsList[this.normalize(channel)] =
-      this.getChatRoomDefaultFieldValues(defaultName);
     // Send the join command, but don't log the channel key.
     this.sendMessage("JOIN", params,
                      "JOIN " + channel + (key ? " <key not logged>" : ""));
     // Open conversation early for better responsiveness.
     let conv = this.getConversation(channel);
+    // Store the prplIChatRoomFieldValues to enable later reconnections.
+    conv._chatRoomFields = this.getChatRoomDefaultFieldValues(defaultName);
     conv.joining = true;
     return conv;
   },
diff --git a/chat/protocols/irc/ircBase.jsm b/chat/protocols/irc/ircBase.jsm
index d014cf3b7d..8b331dc3fc 100644
--- a/chat/protocols/irc/ircBase.jsm
+++ b/chat/protocols/irc/ircBase.jsm
@@ -186,12 +186,7 @@ var ircBase = {
           delete conversation._firstJoin;
 
           // Ensure chatRoomFields information is available for reconnection.
-          let nName = this.normalize(channelName);
-          if (hasOwnProperty(this._chatRoomFieldsList, nName)) {
-            conversation._chatRoomFields = this._chatRoomFieldsList[nName];
-            delete this._chatRoomFieldsList[nName];
-          }
-          else {
+          if (!conversation._chatRoomFields) {
             this.WARN("Opening a MUC without storing its " +
                       "prplIChatRoomFieldValues first.");
             conversation._chatRoomFields =
@@ -199,7 +194,7 @@ var ircBase = {
           }
         }
         else {
-          // Don't worry about adding ourself, RPL_NAMES takes care of that
+          // Don't worry about adding ourself, RPL_NAMREPLY takes care of that
           // case.
           conversation.getParticipant(aMessage.nickname, true);
           let msg = _("message.join", aMessage.nickname, aMessage.source || "");
@@ -1086,8 +1081,8 @@ var ircBase = {
     },
     "403": function(aMessage) { // ERR_NOSUCHCHANNEL
       // <channel name> :No such channel
-      delete this._chatRoomFieldsList[this.normalize(aMessage.params[1])];
-      return conversationErrorMessage(this, aMessage, "error.noChannel");
+      return conversationErrorMessage(this, aMessage, "error.noChannel", true,
+                                      false);
     },
     "404": function(aMessage) { // ERR_CANNOTSENDTOCHAN
       // <channel name> :Cannot send to channel
@@ -1097,9 +1092,8 @@ var ircBase = {
     },
     "405": function(aMessage) { // ERR_TOOMANYCHANNELS
       // <channel name> :You have joined too many channels
-      delete this._chatRoomFieldsList[this.normalize(aMessage.params[1])];
-      return serverErrorMessage(this, aMessage,
-                                _("error.tooManyChannels", aMessage.params[1]));
+      return conversationErrorMessage(this, aMessage, "error.tooManyChannels",
+                                      true);
     },
     "406": function(aMessage) { // ERR_WASNOSUCHNICK
       // <nickname> :There was no such nickname
@@ -1109,8 +1103,8 @@ var ircBase = {
     },
     "407": function(aMessage) { // ERR_TOOMANYTARGETS
       // <target> :<error code> recipients. <abort message>
-      delete this._chatRoomFieldsList[this.normalize(aMessage.params[1])];
-      return conversationErrorMessage(this, aMessage, "error.nonUniqueTarget");
+      return conversationErrorMessage(this, aMessage, "error.nonUniqueTarget",
+                                      false, false);
     },
     "408": function(aMessage) { // ERR_NOSUCHSERVICE
       // <service name> :No such service
@@ -1205,9 +1199,8 @@ var ircBase = {
     },
     "437": function(aMessage) { // ERR_UNAVAILRESOURCE
       // <nick/channel> :Nick/channel is temporarily unavailable
-      // TODO
-      delete this._chatRoomFieldsList[this.normalize(aMessage.params[1])];
-      return false;
+      return conversationErrorMessage(this, aMessage, "error.unavailable",
+                                      true);
     },
     "441": function(aMessage) { // ERR_USERNOTINCHANNEL
       // <nick> <channel> :They aren't on that channel
@@ -1291,9 +1284,8 @@ var ircBase = {
     },
     "471": function(aMessage) { // ERR_CHANNELISFULL
       // <channel> :Cannot join channel (+l)
-      // TODO
-      delete this._chatRoomFieldsList[this.normalize(aMessage.params[1])];
-      return false;
+      return conversationErrorMessage(this, aMessage, "error.channelFull",
+                                      true);
     },
     "472": function(aMessage) { // ERR_UNKNOWNMODE
       // <char> :is unknown mode char to me for <channel>
@@ -1302,35 +1294,22 @@ var ircBase = {
     },
     "473": function(aMessage) { // ERR_INVITEONLYCHAN
       // <channel> :Cannot join channel (+i)
-      // TODO
-      delete this._chatRoomFieldsList[this.normalize(aMessage.params[1])];
-      return false;
+      return conversationErrorMessage(this, aMessage, "error.inviteOnly",
+                                      true, false);
     },
     "474": function(aMessage) { // ERR_BANNEDFROMCHAN
       // <channel> :Cannot join channel (+b)
-      // TODO
-      delete this._chatRoomFieldsList[this.normalize(aMessage.params[1])];
-      return false;
+      return conversationErrorMessage(this, aMessage, "error.channelBanned",
+                                      true, false);
     },
     "475": function(aMessage) { // ERR_BADCHANNELKEY
       // <channel> :Cannot join channel (+k)
-      let channelName = aMessage.params[1];
-
-      // Display an error message to the user.
-      let msg = _("error.wrongKey", channelName);
-      let conversation = this.getConversation(channelName);
-      conversation.writeMessage(aMessage.servername, msg, {system: true});
-
-      // The stored information is out of date, remove it.
-      delete conversation._chatRoomFields;
-      delete this._chatRoomFieldsList[this.normalize(channelName)];
-
-      return true;
+      return conversationErrorMessage(this, aMessage, "error.wrongKey",
+                                      true, false);
     },
     "476": function(aMessage) { // ERR_BADCHANMASK
       // <channel> :Bad Channel Mask
       // TODO
-      delete this._chatRoomFieldsList[this.normalize(aMessage.params[1])];
       return false;
     },
     "477": function(aMessage) { // ERR_NOCHANMODES
diff --git a/chat/protocols/irc/ircUtils.jsm b/chat/protocols/irc/ircUtils.jsm
index 59febffeca..af9c3c4448 100644
--- a/chat/protocols/irc/ircUtils.jsm
+++ b/chat/protocols/irc/ircUtils.jsm
@@ -216,10 +216,25 @@ function mIRCColoring(aStack, aInput) {
   return [stack, output, length];
 }
 
-function conversationErrorMessage(aAccount, aMessage, aError) {
+// Print an error message into a conversation, optionally mark the conversation
+// as not joined and/or not rejoinable.
+function conversationErrorMessage(aAccount, aMessage, aError,
+                                  aJoinFailed = false, aRejoinable = true) {
   let conv = aAccount.getConversation(aMessage.params[1]);
   conv.writeMessage(aMessage.servername, _(aError, aMessage.params[1]),
                     {error: true, system: true});
   delete conv._pendingMessage;
+
+  // Channels have a couple extra things that can be done to them.
+  if (aAccount.isMUCName(aMessage.params[1])) {
+    // If a value for joining is explictly given, mark it.
+    if (aJoinFailed)
+      conv.joining = false;
+    // If the conversation cannot be rejoined automatically, delete
+    // _chatRoomFields.
+    if (!aRejoinable)
+      delete conv._chatRoomFields;
+  }
+
   return true;
 }