diff --git a/Telegram/SourceFiles/app.cpp b/Telegram/SourceFiles/app.cpp
index 8c456aa931..e4c639bcad 100644
--- a/Telegram/SourceFiles/app.cpp
+++ b/Telegram/SourceFiles/app.cpp
@@ -95,7 +95,7 @@ namespace App {
 		return w ? w->mainWidget() : 0;
 	}
 
-	Settings *settings() {
+	SettingsWidget *settings() {
 		Window *w(wnd());
 		return w ? w->settingsWidget() : 0;
 	}
diff --git a/Telegram/SourceFiles/app.h b/Telegram/SourceFiles/app.h
index be6c374c31..fcccf20b31 100644
--- a/Telegram/SourceFiles/app.h
+++ b/Telegram/SourceFiles/app.h
@@ -22,7 +22,7 @@ Copyright (c) 2014 John Preston, https://tdesktop.com
 class Application;
 class Window;
 class MainWidget;
-class Settings;
+class SettingsWidget;
 class Font;
 class Color;
 class FileUploader;
@@ -38,7 +38,7 @@ namespace App {
 	Application *app();
 	Window *wnd();
 	MainWidget *main();
-	Settings *settings();
+	SettingsWidget *settings();
 	FileUploader *uploader();
 
 	void showSettings();
diff --git a/Telegram/SourceFiles/gui/images.cpp b/Telegram/SourceFiles/gui/images.cpp
index c73f8d3af8..b05198e4b1 100644
--- a/Telegram/SourceFiles/gui/images.cpp
+++ b/Telegram/SourceFiles/gui/images.cpp
@@ -230,6 +230,7 @@ bool StorageImage::check() const {
 		h = data.height();
 		invalidateSizeCache();
 		loader->deleteLater();
+		loader->rpcInvalidate();
 		loader = 0;
 
 		saved = bytes;
@@ -256,6 +257,7 @@ void StorageImage::setData(QByteArray &bytes, const QByteArray &format) {
 	invalidateSizeCache();
 	if (loader) {
 		loader->deleteLater();
+		loader->rpcInvalidate();
 		loader = 0;
 	}
 	this->saved = bytes;
@@ -269,6 +271,7 @@ StorageImage::~StorageImage() {
 	}
 	if (loader) {
 		loader->deleteLater();
+		loader->rpcInvalidate();
 		loader = 0;
 	}
 }
diff --git a/Telegram/SourceFiles/history.h b/Telegram/SourceFiles/history.h
index 152c27706c..a3c3e79fc4 100644
--- a/Telegram/SourceFiles/history.h
+++ b/Telegram/SourceFiles/history.h
@@ -227,6 +227,7 @@ struct VideoData {
 		if (l) {
 			l->cancel();
 			l->deleteLater();
+			l->rpcInvalidate();
 		}
 		fileName = QString();
 		modDate = QDateTime();
@@ -241,6 +242,7 @@ struct VideoData {
 			modDate = fileName.isEmpty() ? QDateTime() : QFileInfo(fileName).lastModified();
 		}
 		loader->deleteLater();
+		loader->rpcInvalidate();
 		loader = 0;
 	}
 
@@ -328,6 +330,7 @@ struct AudioData {
 		if (l) {
 			l->cancel();
 			l->deleteLater();
+			l->rpcInvalidate();
 		}
 		fileName = QString();
 		modDate = QDateTime();
@@ -342,6 +345,7 @@ struct AudioData {
 			modDate = fileName.isEmpty() ? QDateTime() : QFileInfo(fileName).lastModified();
 		}
 		loader->deleteLater();
+		loader->rpcInvalidate();
 		loader = 0;
 	}
 
@@ -427,6 +431,7 @@ struct DocumentData {
 		if (l) {
 			l->cancel();
 			l->deleteLater();
+			l->rpcInvalidate();
 		}
 		fileName = QString();
 		modDate = QDateTime();
@@ -441,6 +446,7 @@ struct DocumentData {
 			modDate = fileName.isEmpty() ? QDateTime() : QFileInfo(fileName).lastModified();
 		}
 		loader->deleteLater();
+		loader->rpcInvalidate();
 		loader = 0;
 	}
 
diff --git a/Telegram/SourceFiles/intro/intro.cpp b/Telegram/SourceFiles/intro/intro.cpp
index 9e9416a641..7b8f49f0a2 100644
--- a/Telegram/SourceFiles/intro/intro.cpp
+++ b/Telegram/SourceFiles/intro/intro.cpp
@@ -288,6 +288,12 @@ void IntroWidget::keyPressEvent(QKeyEvent *e) {
 	}
 }
 
+void IntroWidget::rpcInvalidate() {
+	if (phone) phone->rpcInvalidate();
+	if (code) code->rpcInvalidate();
+	if (signup) signup->rpcInvalidate();
+}
+
 IntroWidget::~IntroWidget() {
 	delete steps;
 	delete phone;
diff --git a/Telegram/SourceFiles/intro/intro.h b/Telegram/SourceFiles/intro/intro.h
index c43b0cbb71..0b496e1760 100644
--- a/Telegram/SourceFiles/intro/intro.h
+++ b/Telegram/SourceFiles/intro/intro.h
@@ -57,6 +57,8 @@ public:
 
 	void finish(const MTPUser &user, const QImage &photo = QImage());
 
+	void rpcInvalidate();
+
 	~IntroWidget();
 
 public slots:
diff --git a/Telegram/SourceFiles/mainwidget.cpp b/Telegram/SourceFiles/mainwidget.cpp
index dc2204b37d..8fbf9ec778 100644
--- a/Telegram/SourceFiles/mainwidget.cpp
+++ b/Telegram/SourceFiles/mainwidget.cpp
@@ -756,7 +756,10 @@ void MainWidget::showPeer(const PeerId &peerId, MsgId msgId, bool back, bool for
 	history.showPeer(peerId, msgId, force);
 	if (force || !selectingPeer()) {
 		if (profile) {
-			if (profile) profile->deleteLater();
+			if (profile) {
+				profile->deleteLater();
+				profile->rpcInvalidate();
+			}
 			profile = 0;
 			profileStack.clear();
 			if (!history.peer() || !history.peer()->id) {
@@ -811,7 +814,10 @@ void MainWidget::showPeerProfile(const PeerData *peer, bool back) {
 			profileStack.push_back(history.peer());
 		}
 	}
-	if (profile) profile->deleteLater();
+	if (profile) {
+		profile->deleteLater();
+		profile->rpcInvalidate();
+	}
 	profile = new ProfileWidget(this, peer);
 	_topBar.show();
 	resizeEvent(0);
diff --git a/Telegram/SourceFiles/mtproto/mtpConnection.cpp b/Telegram/SourceFiles/mtproto/mtpConnection.cpp
index ad786002dd..e685714995 100644
--- a/Telegram/SourceFiles/mtproto/mtpConnection.cpp
+++ b/Telegram/SourceFiles/mtproto/mtpConnection.cpp
@@ -1034,7 +1034,8 @@ void MTProtoConnectionPrivate::createConn() {
 MTProtoConnectionPrivate::MTProtoConnectionPrivate(QThread *thread, MTProtoConnection *owner, MTPSessionData *data, uint32 _dc)
 	: QObject(0)
 	, _state(MTProtoConnection::Disconnected)
-    , dc(_dc)
+	, _needSessionReset(false)
+	, dc(_dc)
     , _owner(owner)
     , conn(0)
     , retryTimeout(1)
@@ -1137,7 +1138,118 @@ bool MTProtoConnectionPrivate::setState(int32 state, int32 ifState) {
 	return true;
 }
 
-mtpMsgId MTProtoConnectionPrivate::prepareToSend(mtpRequest &request) {
+void MTProtoConnectionPrivate::resetSession() { // recreate all msg_id and msg_seqno
+	_needSessionReset = false;
+
+	QWriteLocker locker1(sessionData->haveSentMutex());
+	QWriteLocker locker2(sessionData->toResendMutex());
+	QWriteLocker locker3(sessionData->toSendMutex());
+	QWriteLocker locker4(sessionData->wereAckedMutex());
+	mtpRequestMap &haveSent(sessionData->haveSentMap());
+	mtpRequestIdsMap &toResend(sessionData->toResendMap());
+	mtpPreRequestMap &toSend(sessionData->toSendMap());
+	mtpRequestIdsMap &wereAcked(sessionData->wereAckedMap());
+
+	mtpMsgId newId = msgid();
+	mtpRequestMap setSeqNumbers;
+	typedef QMap<mtpMsgId, mtpMsgId> Replaces;
+	Replaces replaces;
+	for (mtpRequestMap::const_iterator i = haveSent.cbegin(), e = haveSent.cend(); i != e; ++i) {
+		if (!mtpRequestData::isSentContainer(i.value())) {
+			if (!*(mtpMsgId*)(i.value()->constData() + 4)) continue;
+
+			mtpMsgId id = i.key();
+			if (id > newId) {
+				while (true) {
+					if (toResend.constFind(newId) == toResend.cend() && wereAcked.constFind(newId) == wereAcked.cend() && haveSent.constFind(newId) == haveSent.cend()) {
+						break;
+					}
+					mtpMsgId m = msgid();
+					if (m <= newId) break; // wtf
+
+					newId = m;
+				}
+
+				MTP_LOG(dc, ("Replacing msgId %1 to %2!").arg(id).arg(newId));
+				replaces.insert(id, newId);
+				id = newId;
+				*(mtpMsgId*)(i.value()->data() + 4) = id;
+			}
+			setSeqNumbers.insert(id, i.value());
+		}
+	}
+	for (mtpRequestIdsMap::const_iterator i = toResend.cbegin(), e = toResend.cend(); i != e; ++i) { // collect all non-container requests
+		mtpPreRequestMap::const_iterator j = toSend.constFind(i.value());
+		if (j == toSend.cend()) continue;
+
+		if (!mtpRequestData::isSentContainer(j.value())) {
+			if (!*(mtpMsgId*)(j.value()->constData() + 4)) continue;
+
+			mtpMsgId id = i.key();
+			if (id > newId) {
+				while (true) {
+					if (toResend.constFind(newId) == toResend.cend() && wereAcked.constFind(newId) == wereAcked.cend() && haveSent.constFind(newId) == haveSent.cend()) {
+						break;
+					}
+					mtpMsgId m = msgid();
+					if (m <= newId) break; // wtf
+
+					newId = m;
+				}
+
+				MTP_LOG(dc, ("Replacing msgId %1 to %2!").arg(id).arg(newId));
+				replaces.insert(id, newId);
+				id = newId;
+				*(mtpMsgId*)(j.value()->data() + 4) = id;
+			}
+			setSeqNumbers.insert(id, j.value());
+		}
+	}
+
+	uint64 session = MTP::nonce<uint64>();
+	DEBUG_LOG(("MTP Info: creating new session after bad_msg_notification, setting random server_session %1").arg(session));
+	sessionData->setSession(session);
+
+	for (mtpRequestMap::const_iterator i = setSeqNumbers.cbegin(), e = setSeqNumbers.cend(); i != e; ++i) { // generate new seq_numbers
+		bool wasNeedAck = (*(i.value()->data() + 6) & 1);
+		*(i.value()->data() + 6) = sessionData->nextRequestSeqNumber(wasNeedAck);
+	}
+	if (!replaces.isEmpty()) {
+		for (Replaces::const_iterator i = replaces.cbegin(), e = replaces.cend(); i != e; ++i) { // replace msgIds keys in all data structs
+			mtpRequestMap::iterator j = haveSent.find(i.key());
+			if (j != haveSent.cend()) {
+				mtpRequest req = j.value();
+				haveSent.erase(j);
+				haveSent.insert(i.value(), req);
+			}
+			mtpRequestIdsMap::iterator k = toResend.find(i.key());
+			if (k != toResend.cend()) {
+				mtpRequestId req = k.value();
+				toResend.erase(k);
+				toResend.insert(i.value(), req);
+			}
+			k = wereAcked.find(i.key());
+			if (k != wereAcked.cend()) {
+				mtpRequestId req = k.value();
+				wereAcked.erase(k);
+				wereAcked.insert(i.value(), req);
+			}
+		}
+		for (mtpRequestMap::const_iterator i = haveSent.cbegin(), e = haveSent.cend(); i != e; ++i) { // replace msgIds in saved containers
+			if (mtpRequestData::isSentContainer(i.value())) {
+				mtpMsgId *ids = (mtpMsgId *)(i.value()->data() + 8);
+				for (uint32 j = 0, l = (i.value()->size() - 8) >> 1; j < l; ++j) {
+					Replaces::const_iterator k = replaces.constFind(ids[j]);
+					if (k != replaces.cend()) {
+						ids[j] = k.value();
+					}
+				}
+			}
+		}
+	}
+}
+
+mtpMsgId MTProtoConnectionPrivate::prepareToSend(mtpRequest &request, mtpMsgId currentLastId) {
 	if (request->size() < 9) return 0;
 	mtpMsgId msgId = *(mtpMsgId*)(request->constData() + 4);
 	if (msgId) { // resending this request
@@ -1148,12 +1260,75 @@ mtpMsgId MTProtoConnectionPrivate::prepareToSend(mtpRequest &request) {
 			toResend.erase(i);
 		}
 	} else {
-		msgId = *(mtpMsgId*)(request->data() + 4) = msgid();
+		msgId = *(mtpMsgId*)(request->data() + 4) = currentLastId;
 		*(request->data() + 6) = sessionData->nextRequestSeqNumber(mtpRequestData::needAck(request));
 	}
 	return msgId;
 }
 
+mtpMsgId MTProtoConnectionPrivate::replaceMsgId(mtpRequest &request, mtpMsgId newId) {
+	if (request->size() < 9) return 0;
+
+	mtpMsgId oldMsgId = *(mtpMsgId*)(request->constData() + 4);
+	if (oldMsgId != newId) {
+		if (oldMsgId) {
+			QWriteLocker locker(sessionData->toResendMutex());
+			// haveSentMutex() and wereAckedMutex() were locked in tryToSend()
+
+			mtpRequestIdsMap &toResend(sessionData->toResendMap());
+			mtpRequestIdsMap &wereAcked(sessionData->wereAckedMap());
+			mtpRequestMap &haveSent(sessionData->haveSentMap());
+
+			while (true) {
+				if (toResend.constFind(newId) == toResend.cend() && wereAcked.constFind(newId) == wereAcked.cend() && haveSent.constFind(newId) == haveSent.cend()) {
+					break;
+				}
+				mtpMsgId m = msgid();
+				if (m <= newId) break; // wtf
+				
+				newId = m;
+			}
+
+			mtpRequestIdsMap::iterator i = toResend.find(oldMsgId);
+			if (i != toResend.cend()) {
+				mtpRequestId req = i.value();
+				toResend.erase(i);
+				toResend.insert(newId, req);
+			}
+
+			mtpRequestIdsMap::iterator j = wereAcked.find(oldMsgId);
+			if (j != wereAcked.cend()) {
+				mtpRequestId req = j.value();
+				wereAcked.erase(j);
+				wereAcked.insert(newId, req);
+			}
+
+			mtpRequestMap::iterator k = haveSent.find(oldMsgId);
+			if (k != haveSent.cend()) {
+				mtpRequest req = k.value();
+				haveSent.erase(k);
+				haveSent.insert(newId, req);
+			}
+
+			for (k = haveSent.begin(); k != haveSent.cend(); ++k) {
+				mtpRequest req(k.value());
+				if (mtpRequestData::isSentContainer(req)) {
+					mtpMsgId *ids = (mtpMsgId *)(req->data() + 8);
+					for (uint32 i = 0, l = (req->size() - 8) >> 1; i < l; ++i) {
+						if (ids[i] == oldMsgId) {
+							ids[i] = newId;
+						}
+					}
+				}
+			}
+		} else {
+			*(request->data() + 6) = sessionData->nextRequestSeqNumber(mtpRequestData::needAck(request));
+		}
+		*(mtpMsgId*)(request->data() + 4) = newId;
+	}
+	return newId;
+}
+
 void MTProtoConnectionPrivate::tryToSend() {
 	if (!conn) return;
 
@@ -1211,7 +1386,7 @@ void MTProtoConnectionPrivate::tryToSend() {
 				locker1.unlock();
 			}
 
-			mtpMsgId msgId = prepareToSend(toSendRequest);
+			mtpMsgId msgId = prepareToSend(toSendRequest, msgid());
 			if (havePrepend) pingMsgId = msgId;
 
 			if (toSendRequest->requestId) {
@@ -1237,10 +1412,12 @@ void MTProtoConnectionPrivate::tryToSend() {
 			toSendRequest->push_back(mtpc_msg_container);
 			toSendRequest->push_back(toSendCount);
 
-			QWriteLocker locker2(sessionData->haveSentMutex());
+			mtpMsgId bigMsgId = msgid(); // check for a valid container
+
+			QWriteLocker locker2(sessionData->haveSentMutex()); // the fact of this lock is used in replaceMsgId()
 			mtpRequestMap &haveSent(sessionData->haveSentMap());
 
-			QWriteLocker locker3(sessionData->wereAckedMutex());
+			QWriteLocker locker3(sessionData->wereAckedMutex()); // the fact of this lock is used in replaceMsgId()
 			mtpRequestIdsMap &wereAcked(sessionData->wereAckedMap());
 
 			mtpRequest haveSentIdsWrap(mtpRequestData::prepare(idsWrapSize)); // prepare "request-like" wrap for msgId vector
@@ -1249,7 +1426,9 @@ void MTProtoConnectionPrivate::tryToSend() {
 			mtpMsgId *haveSentArr = (mtpMsgId*)(haveSentIdsWrap->data() + 8);
 
 			if (havePrepend) {
-				mtpMsgId msgId = prepareToSend(prepend);
+				mtpMsgId msgId = prepareToSend(prepend, bigMsgId);
+				if (msgId > bigMsgId) msgId = replaceMsgId(prepend, bigMsgId);
+				if (msgId >= bigMsgId) bigMsgId = msgid();
 				*(haveSentArr++) = msgId;
 				if (havePrepend) pingMsgId = msgId;
 
@@ -1261,8 +1440,10 @@ void MTProtoConnectionPrivate::tryToSend() {
 			}
 			for (mtpPreRequestMap::iterator i = toSend.begin(), e = toSend.end(); i != e; ++i) {
 				mtpRequest &req(i.value());
-				mtpMsgId msgId = prepareToSend(req);
-				*(haveSentArr++) = msgId;				
+				mtpMsgId msgId = prepareToSend(req, bigMsgId);
+				if (msgId > bigMsgId) msgId = replaceMsgId(req, bigMsgId);
+				if (msgId >= bigMsgId) bigMsgId = msgid();
+				*(haveSentArr++) = msgId;
 
 				if (req->requestId) {
 					if (mtpRequestData::needAck(req)) {
@@ -1279,7 +1460,7 @@ void MTProtoConnectionPrivate::tryToSend() {
 				memcpy(toSendRequest->data() + from, req->constData() + 4, len * sizeof(mtpPrime));
 			}
 
-			mtpMsgId contMsgId = prepareToSend(toSendRequest);
+			mtpMsgId contMsgId = prepareToSend(toSendRequest, bigMsgId);
 			*(mtpMsgId*)(haveSentIdsWrap->data() + 4) = contMsgId;
 			(*haveSentIdsWrap)[6] = 0; // for container, msDate = 0, seqNo = 0
 			haveSent.insert(contMsgId, haveSentIdsWrap);
@@ -1372,6 +1553,9 @@ void MTProtoConnectionPrivate::restart(bool maybeBadKey) {
 	}
 
 	doDisconnect();
+	if (_needSessionReset) {
+		resetSession();
+	}
 	restarted = true;
 	if (retryTimer.isActive()) return;
 
@@ -1564,7 +1748,9 @@ void MTProtoConnectionPrivate::handleReceived() {
 		int32 res = 1; // if no need to handle, then succeed
 		end = data + 8 + (msgLen >> 2);
 		const mtpPrime *sfrom(data + 4);
-		MTP_LOG(dc, ("Recv: ") + mtpTextSerialize(sfrom, end, mtpc_core_message));
+		if (cDebug()) {
+			MTP_LOG(dc, ("Recv: ") + mtpTextSerialize(sfrom, end, mtpc_core_message));
+		}
 
 		bool needToHandle = false;
 		{
@@ -1606,6 +1792,7 @@ void MTProtoConnectionPrivate::handleReceived() {
 		}
 
 		if (res < 0) {
+			_needSessionReset = (res < -1);
 			return restart();
 		}
 
@@ -1714,29 +1901,71 @@ int32 MTProtoConnectionPrivate::handleOneReceived(const mtpPrime *from, const mt
 		const MTPDbad_msg_notification &data(msg.c_bad_msg_notification());
 		LOG(("Message Info: bad message notification received (error_code %3) for msg_id = %1, seq_no = %2").arg(data.vbad_msg_id.v).arg(data.vbad_msg_seqno.v).arg(data.verror_code.v));
 
-		bool needResend = (data.verror_code.v == 16 || data.verror_code.v == 17); // bad msg_id
-		
-		mtpMsgId resendId = data.vbad_msg_id.v;
-		if (!wasSent(resendId)) {
-			DEBUG_LOG(("Message Error: such message was not sent recently %1").arg(resendId));
-			return (badTime ? 0 : 1);
-		}
+		int32 errorCode = data.verror_code.v;
+		if (errorCode == 16 || errorCode == 17 || errorCode == 32 || errorCode == 33 || errorCode == 64) { // can handle
+			bool needResend = (errorCode == 16 || errorCode == 17); // bad msg_id
+			if (errorCode == 64) { // bad container!
+				needResend = true;
+				if (cDebug()) {
+					mtpRequest request;
+					{
+						QWriteLocker locker(sessionData->haveSentMutex());
+						mtpRequestMap &haveSent(sessionData->haveSentMap());
 
-		if (needResend) { // bad msg_id
-			if (serverSalt) sessionData->setSalt(serverSalt);
-			unixtimeSet(serverTime, true);
+						mtpRequestMap::iterator i = haveSent.find(msgId);
+						if (i == haveSent.end()) {
+							LOG(("Message Error: Container not found!"));
+						}
 
-			DEBUG_LOG(("Message Info: unixtime updated, now %1, resending in container..").arg(serverTime));
-
-			resend(resendId, 0, true);
-		} else {
-			if (badTime) {
-				if (serverSalt) sessionData->setSalt(serverSalt);
-				unixtimeSet(serverTime);
-				badTime = false;
+						request = i.value();
+					}
+					if (request) {
+						if (mtpRequestData::isSentContainer(request)) {
+							QStringList lst;
+							const mtpMsgId *ids = (const mtpMsgId *)(request->constData() + 8);
+							for (uint32 i = 0, l = (request->size() - 8) >> 1; i < l; ++i) {
+								lst.push_back(QString::number(ids[i]));
+							}
+							LOG(("Message Info: bad container received! messages: %1").arg(lst.join(',')));
+						} else {
+							LOG(("Message Error: bad container received, but request is not a container!"));
+						}
+					}
+				}
 			}
-			LOG(("Message Error: bad message notification received, msgId %1, error_code %2").arg(data.vbad_msg_id.v).arg(data.verror_code.v));
-			return -1;
+
+			mtpMsgId resendId = data.vbad_msg_id.v;
+			if (!wasSent(resendId)) {
+				DEBUG_LOG(("Message Error: such message was not sent recently %1").arg(resendId));
+				return (badTime ? 0 : 1);
+			}
+
+			if (needResend) { // bad msg_id
+				if (serverSalt) sessionData->setSalt(serverSalt);
+				unixtimeSet(serverTime, true);
+
+				DEBUG_LOG(("Message Info: unixtime updated, now %1, resending in container..").arg(serverTime));
+
+				resend(resendId, 0, true);
+			} else { // must create new session, because msg_id and msg_seqno are inconsistent
+				if (badTime) {
+					if (serverSalt) sessionData->setSalt(serverSalt);
+					unixtimeSet(serverTime);
+					badTime = false;
+				}
+				LOG(("Message Info: bad message notification received, msgId %1, error_code %2").arg(data.vbad_msg_id.v).arg(errorCode));
+				return -2;
+			}
+		} else { // fatal (except 48, but it must not get here)
+			mtpMsgId resendId = data.vbad_msg_id.v;
+			mtpRequestId requestId = wasSent(resendId);
+			if (requestId) {
+				LOG(("Message Error: bad message notification received, msgId %1, error_code %2, fatal: clearing callbacks").arg(data.vbad_msg_id.v).arg(errorCode));
+				_mtp_internal::clearCallbacksDelayed(RPCCallbackClears(1, RPCCallbackClear(requestId, -errorCode)));
+			} else {
+				DEBUG_LOG(("Message Error: such message was not sent recently %1").arg(resendId));
+			}
+			return (badTime ? 0 : 1);
 		}
 	} return 1;
 
@@ -1855,8 +2084,13 @@ int32 MTProtoConnectionPrivate::handleOneReceived(const mtpPrime *from, const mt
 		}
 		try {
 			const mtpPrime *rFrom = requestBuffer->constData() + 8, *rEnd = requestBuffer->constData() + requestBuffer->size();
-			MTPMsgsStateReq request(rFrom, rEnd);
-			handleMsgsStates(request.c_msgs_state_req().vmsg_ids.c_vector().v, states, toAck);
+			if (*rFrom == mtpc_msgs_state_req) {
+				MTPMsgsStateReq request(rFrom, rEnd);
+				handleMsgsStates(request.c_msgs_state_req().vmsg_ids.c_vector().v, states, toAck);
+			} else {
+				MTPMsgResendReq request(rFrom, rEnd);
+				handleMsgsStates(request.c_msg_resend_req().vmsg_ids.c_vector().v, states, toAck);
+			}
 		} catch(Exception &e) {
 			LOG(("Message Error: could not parse sent msgs_state_req"));
 			throw;
@@ -2280,7 +2514,6 @@ mtpRequestId MTProtoConnectionPrivate::resend(mtpMsgId msgId, uint64 msCanWait,
 	return sessionData->owner()->resend(msgId, msCanWait, forceContainer, sendMsgStateInfo);
 }
 
-
 void MTProtoConnectionPrivate::onConnected() {
 	disconnect(conn, SIGNAL(connected()), this, SLOT(onConnected()));
 	if (!conn->isConnected()) {
@@ -2874,7 +3107,9 @@ bool MTProtoConnectionPrivate::sendRequest(mtpRequest &request, bool needAnyResp
 	memcpy(request->data() + 2, &session, 2 * sizeof(mtpPrime));
 
 	const mtpPrime *from = request->constData() + 4;
-	MTP_LOG(dc, ("Send: ") + mtpTextSerialize(from, from + messageSize, mtpc_core_message));
+	if (cDebug()) {
+		MTP_LOG(dc, ("Send: ") + mtpTextSerialize(from, from + messageSize, mtpc_core_message));
+	}
 
 	uchar encryptedSHA[20];
 	MTPint128 &msgKey(*(MTPint128*)(encryptedSHA + 4));
diff --git a/Telegram/SourceFiles/mtproto/mtpConnection.h b/Telegram/SourceFiles/mtproto/mtpConnection.h
index 25fafbc7ee..4c243bc5fa 100644
--- a/Telegram/SourceFiles/mtproto/mtpConnection.h
+++ b/Telegram/SourceFiles/mtproto/mtpConnection.h
@@ -332,7 +332,8 @@ private:
 
 	void createConn();
 
-	mtpMsgId prepareToSend(mtpRequest &request);
+	mtpMsgId prepareToSend(mtpRequest &request, mtpMsgId currentLastId);
+	mtpMsgId replaceMsgId(mtpRequest &request, mtpMsgId newId);
 
 	bool sendRequest(mtpRequest &request, bool needAnyResponse);
 	mtpRequestId wasSent(mtpMsgId msgId) const;
@@ -347,6 +348,9 @@ private:
 	mutable QReadWriteLock stateMutex;
 	int32 _state;
 
+	bool _needSessionReset;
+	void resetSession();
+
 	uint32 dc;
 	MTProtoConnection *_owner;
 	MTPabstractConnection *conn;
diff --git a/Telegram/SourceFiles/mtproto/mtpRPC.cpp b/Telegram/SourceFiles/mtproto/mtpRPC.cpp
index b2d01e005c..abae4c6585 100644
--- a/Telegram/SourceFiles/mtproto/mtpRPC.cpp
+++ b/Telegram/SourceFiles/mtproto/mtpRPC.cpp
@@ -19,17 +19,17 @@ Copyright (c) 2014 John Preston, https://tdesktop.com
 #include "mtproto/mtpRPC.h"
 
 RPCOwnedDoneHandler::RPCOwnedDoneHandler(RPCSender *owner) : _owner(owner) {
-	_owner->regHandler(this);
+	_owner->_rpcRegHandler(this);
 }
 
 RPCOwnedDoneHandler::~RPCOwnedDoneHandler() {
-	if (_owner) _owner->unregHandler(this);
+	if (_owner) _owner->_rpcUnregHandler(this);
 }
 
 RPCOwnedFailHandler::RPCOwnedFailHandler(RPCSender *owner) : _owner(owner) {
-	_owner->regHandler(this);
+	_owner->_rpcRegHandler(this);
 }
 
 RPCOwnedFailHandler::~RPCOwnedFailHandler() {
-	if (_owner) _owner->unregHandler(this);
+	if (_owner) _owner->_rpcUnregHandler(this);
 }
diff --git a/Telegram/SourceFiles/mtproto/mtpRPC.h b/Telegram/SourceFiles/mtproto/mtpRPC.h
index f27438b30c..00a4f977d0 100644
--- a/Telegram/SourceFiles/mtproto/mtpRPC.h
+++ b/Telegram/SourceFiles/mtproto/mtpRPC.h
@@ -654,9 +654,28 @@ private:
 
 class RPCSender {
 	typedef QSet<RPCOwnedDoneHandler*> DoneHandlers;
-	DoneHandlers doneHandlers;
+	DoneHandlers _rpcDoneHandlers;
 	typedef QSet<RPCOwnedFailHandler*> FailHandlers;
-	FailHandlers failHandlers;
+	FailHandlers _rpcFailHandlers;
+
+	void _rpcRegHandler(RPCOwnedDoneHandler *handler) {
+		_rpcDoneHandlers.insert(handler);
+	}
+
+	void _rpcUnregHandler(RPCOwnedDoneHandler *handler) {
+		_rpcDoneHandlers.remove(handler);
+	}
+
+	void _rpcRegHandler(RPCOwnedFailHandler *handler) {
+		_rpcFailHandlers.insert(handler);
+	}
+
+	void _rpcUnregHandler(RPCOwnedFailHandler *handler) {
+		_rpcFailHandlers.remove(handler);
+	}
+
+	friend class RPCOwnedDoneHandler;
+	friend class RPCOwnedFailHandler;
 
 public:
 
@@ -760,29 +779,19 @@ public:
 		return RPCFailHandlerPtr(new RPCBindedFailHandlerOwnedNo<T, TReceiver>(b, static_cast<TReceiver*>(this), onFail));
 	}
 
-	void regHandler(RPCOwnedDoneHandler *handler) {
-		doneHandlers.insert(handler);
-	}
-
-	void unregHandler(RPCOwnedDoneHandler *handler) {
-		doneHandlers.remove(handler);
-	}
-
-	void regHandler(RPCOwnedFailHandler *handler) {
-		failHandlers.insert(handler);
-	}
-
-	void unregHandler(RPCOwnedFailHandler *handler) {
-		failHandlers.remove(handler);
+	void rpcInvalidate() {
+		for (DoneHandlers::iterator i = _rpcDoneHandlers.begin(), e = _rpcDoneHandlers.end(); i != e; ++i) {
+			(*i)->invalidate();
+		}
+		_rpcDoneHandlers.clear();
+		for (FailHandlers::iterator i = _rpcFailHandlers.begin(), e = _rpcFailHandlers.end(); i != e; ++i) {
+			(*i)->invalidate();
+		}
+		_rpcFailHandlers.clear();
 	}
 
 	~RPCSender() {
-		for (DoneHandlers::iterator i = doneHandlers.begin(), e = doneHandlers.end(); i != e; ++i) {
-			(*i)->invalidate();
-		}
-		for (FailHandlers::iterator i = failHandlers.begin(), e = failHandlers.end(); i != e; ++i) {
-			(*i)->invalidate();
-		}
+		rpcInvalidate();
 	}
 
 };
diff --git a/Telegram/SourceFiles/mtproto/mtpSession.h b/Telegram/SourceFiles/mtproto/mtpSession.h
index eb2220f432..bc64026c94 100644
--- a/Telegram/SourceFiles/mtproto/mtpSession.h
+++ b/Telegram/SourceFiles/mtproto/mtpSession.h
@@ -61,8 +61,7 @@ public:
 	void setKey(const mtpAuthKeyPtr &key) {
 		if (authKey != key) {
 			uint64 session;
-			memset_rand(&session, sizeof(uint64));
-
+			memsetrnd(session);
 			authKey = key;
 
 			DEBUG_LOG(("MTP Info: new auth key set in SessionData, id %1, setting random server_session %2").arg(key ? key->keyId() : 0).arg(session));
diff --git a/Telegram/SourceFiles/settingswidget.cpp b/Telegram/SourceFiles/settingswidget.cpp
index 2fc51d4de0..1b3fe62c2d 100644
--- a/Telegram/SourceFiles/settingswidget.cpp
+++ b/Telegram/SourceFiles/settingswidget.cpp
@@ -95,7 +95,7 @@ bool scaleIs(DBIScale scale) {
 	return cRealScale() == scale || (cRealScale() == dbisAuto && cScreenScale() == scale);
 }
 
-SettingsInner::SettingsInner(Settings *parent) : QWidget(parent),
+SettingsInner::SettingsInner(SettingsWidget *parent) : QWidget(parent),
 	_self(App::self()),
 
 	// profile
@@ -1126,7 +1126,7 @@ void SettingsInner::onPhotoUpdateDone(PeerId peer) {
 	update();
 }
 
-Settings::Settings(Window *parent) : QWidget(parent),
+SettingsWidget::SettingsWidget(Window *parent) : QWidget(parent),
 	_scroll(this, st::setScroll), _inner(this), _close(this, st::setClose) {
 	_scroll.setWidget(&_inner);
 
@@ -1138,11 +1138,11 @@ Settings::Settings(Window *parent) : QWidget(parent),
 	showAll();
 }
 
-void Settings::onParentResize(const QSize &newSize) {
+void SettingsWidget::onParentResize(const QSize &newSize) {
 	resize(newSize);
 }
 
-void Settings::animShow(const QPixmap &bgAnimCache, bool back) {
+void SettingsWidget::animShow(const QPixmap &bgAnimCache, bool back) {
 	_bgAnimCache = bgAnimCache;
 
 	anim::stop(this);
@@ -1159,7 +1159,7 @@ void Settings::animShow(const QPixmap &bgAnimCache, bool back) {
 	show();
 }
 
-bool Settings::animStep(float64 ms) {
+bool SettingsWidget::animStep(float64 ms) {
 	float64 fullDuration = st::introSlideDelta + st::introSlideDuration, dt = ms / fullDuration;
 	float64 dt1 = (ms > st::introSlideDuration) ? 1 : (ms / st::introSlideDuration), dt2 = (ms > st::introSlideDelta) ? (ms - st::introSlideDelta) / (st::introSlideDuration) : 0;
 	bool res = true;
@@ -1184,7 +1184,7 @@ bool Settings::animStep(float64 ms) {
 	return res;
 }
 
-void Settings::paintEvent(QPaintEvent *e) {
+void SettingsWidget::paintEvent(QPaintEvent *e) {
 	QRect r(e->rect());
 	bool trivial = (rect() == r);
 
@@ -1202,32 +1202,32 @@ void Settings::paintEvent(QPaintEvent *e) {
 	}
 }
 
-void Settings::showAll() {
+void SettingsWidget::showAll() {
 	_scroll.show();
 	_inner.show();
 	_inner.showAll();
 	_close.show();
 }
 
-void Settings::hideAll() {
+void SettingsWidget::hideAll() {
 	_scroll.hide();
 	_close.hide();
 }
 
-void Settings::resizeEvent(QResizeEvent *e) {
+void SettingsWidget::resizeEvent(QResizeEvent *e) {
 	_scroll.resize(size());
 	_inner.updateSize(width());
 	_close.move(st::setClosePos.x(), st::setClosePos.y());
 }
 
-void Settings::dragEnterEvent(QDragEnterEvent *e) {
+void SettingsWidget::dragEnterEvent(QDragEnterEvent *e) {
 
 }
 
-void Settings::dropEvent(QDropEvent *e) {
+void SettingsWidget::dropEvent(QDropEvent *e) {
 }
 
-bool Settings::getPhotoCoords(PhotoData *photo, int32 &x, int32 &y, int32 &w) const {
+bool SettingsWidget::getPhotoCoords(PhotoData *photo, int32 &x, int32 &y, int32 &w) const {
 	if (_inner.getPhotoCoords(photo, x, y, w)) {
 		x += _inner.x();
 		y += _inner.y();
@@ -1236,14 +1236,18 @@ bool Settings::getPhotoCoords(PhotoData *photo, int32 &x, int32 &y, int32 &w) co
 	return false;
 }
 
-void Settings::updateOnlineDisplay() {
+void SettingsWidget::updateOnlineDisplay() {
 	_inner.updateOnlineDisplay();
 }
 
-void Settings::updateConnectionType() {
+void SettingsWidget::updateConnectionType() {
 	_inner.updateConnectionType();
 }
 
-Settings::~Settings() {
+void SettingsWidget::rpcInvalidate() {
+	_inner.rpcInvalidate();
+}
+
+SettingsWidget::~SettingsWidget() {
 	if (App::wnd()) App::wnd()->noSettings(this);
 }
diff --git a/Telegram/SourceFiles/settingswidget.h b/Telegram/SourceFiles/settingswidget.h
index 64c114910f..fdf57c9578 100644
--- a/Telegram/SourceFiles/settingswidget.h
+++ b/Telegram/SourceFiles/settingswidget.h
@@ -59,7 +59,7 @@ class SettingsInner : public QWidget, public RPCSender, public Animated {
 
 public:
 
-	SettingsInner(Settings *parent);
+	SettingsInner(SettingsWidget *parent);
 
 	void paintEvent(QPaintEvent *e);
 	void resizeEvent(QResizeEvent *e);
@@ -218,12 +218,12 @@ private:
 
 };
 
-class Settings : public QWidget, public Animated {
+class SettingsWidget : public QWidget, public Animated {
 	Q_OBJECT
 
 public:
 
-	Settings(Window *parent);
+	SettingsWidget(Window *parent);
 
 	void paintEvent(QPaintEvent *e);
 	void resizeEvent(QResizeEvent *e);
@@ -238,7 +238,9 @@ public:
 	void updateOnlineDisplay();
 	void updateConnectionType();
 
-	~Settings();
+	void rpcInvalidate();
+
+	~SettingsWidget();
 
 public slots:
 
diff --git a/Telegram/SourceFiles/types.h b/Telegram/SourceFiles/types.h
index 71480ed461..c0f7c7a945 100644
--- a/Telegram/SourceFiles/types.h
+++ b/Telegram/SourceFiles/types.h
@@ -129,6 +129,11 @@ inline char *hashMd5Hex(const void *data, uint32 len, void *dest) { // dest = pt
 
 void memset_rand(void *data, uint32 len);
 
+template <typename T>
+inline void memsetrnd(T &value) {
+	memset_rand(&value, sizeof(value));
+}
+
 class ReadLockerAttempt {
 public:
 
diff --git a/Telegram/SourceFiles/window.cpp b/Telegram/SourceFiles/window.cpp
index 44a3be1ae1..8fedbf2575 100644
--- a/Telegram/SourceFiles/window.cpp
+++ b/Telegram/SourceFiles/window.cpp
@@ -395,18 +395,21 @@ void Window::clearWidgets() {
 		anim::stop(settings);
 		settings->hide();
 		settings->deleteLater();
+		settings->rpcInvalidate();
 		settings = 0;
 	}
 	if (main) {
 		anim::stop(main);
 		main->hide();
 		main->deleteLater();
+		main->rpcInvalidate();
 		main = 0;
 	}
 	if (intro) {
 		anim::stop(intro);
 		intro->hide();
 		intro->deleteLater();
+		intro->rpcInvalidate();
 		intro = 0;
 	}
 }
@@ -463,7 +466,7 @@ void Window::showSettings() {
 		anim::stop(main);
 		main->hide();
 	}
-	settings = new Settings(this);
+	settings = new SettingsWidget(this);
 	settings->animShow(bg);
 
 	fixOrder();
@@ -476,6 +479,7 @@ void Window::hideSettings(bool fast) {
 		anim::stop(settings);
 		settings->hide();
 		settings->deleteLater();
+		settings->rpcInvalidate();
 		settings = 0;
 		if (intro) {
 			intro->show();
@@ -488,6 +492,7 @@ void Window::hideSettings(bool fast) {
 		anim::stop(settings);
 		settings->hide();
 		settings->deleteLater();
+		settings->rpcInvalidate();
 		settings = 0;
 		if (intro) {
 			intro->animShow(bg, true);
@@ -533,7 +538,7 @@ MainWidget *Window::mainWidget() {
 	return main;
 }
 
-Settings *Window::settingsWidget() {
+SettingsWidget *Window::settingsWidget() {
 	return settings;
 }
 
@@ -798,7 +803,7 @@ void Window::noIntro(IntroWidget *was) {
 	}
 }
 
-void Window::noSettings(Settings *was) {
+void Window::noSettings(SettingsWidget *was) {
 	if (was == settings) {
 		settings = 0;
 	}
diff --git a/Telegram/SourceFiles/window.h b/Telegram/SourceFiles/window.h
index b4989db4aa..838379a43d 100644
--- a/Telegram/SourceFiles/window.h
+++ b/Telegram/SourceFiles/window.h
@@ -25,7 +25,7 @@ Copyright (c) 2014 John Preston, https://tdesktop.com
 class TitleWidget;
 class IntroWidget;
 class MainWidget;
-class Settings;
+class SettingsWidget;
 class LayerWidget;
 class BackgroundWidget;
 class LayeredWidget;
@@ -165,7 +165,7 @@ public:
 	
 	IntroWidget *introWidget();
 	MainWidget *mainWidget();
-	Settings *settingsWidget();
+	SettingsWidget *settingsWidget();
 
 	void showConnecting(const QString &text, const QString &reconnect = QString());
 	void hideConnecting();
@@ -191,7 +191,7 @@ public:
 	void activate();
 
 	void noIntro(IntroWidget *was);
-	void noSettings(Settings *was);
+	void noSettings(SettingsWidget *was);
 	void noMain(MainWidget *was);
 	void noLayer(LayerWidget *was);
 	void noBox(BackgroundWidget *was);
@@ -259,7 +259,7 @@ private:
 	TitleWidget *title;
 	IntroWidget *intro;
 	MainWidget *main;
-	Settings *settings;
+	SettingsWidget *settings;
 	LayerWidget *layer;
 	BackgroundWidget *layerBG;