diff --git a/client/communicator.cpp b/client/communicator.cpp
index 0dd3ca3c5..04a4e811d 100644
--- a/client/communicator.cpp
+++ b/client/communicator.cpp
@@ -45,7 +45,7 @@ void Communicator::onLineAvailable(const QString& line)
     emit messageReceived(message);
 }
 
-bool Communicator::connected() const
+bool Communicator::isConnected() const
 {
     if (!m_localClient) {
         return false;
@@ -66,7 +66,7 @@ bool Communicator::writeData(const QString& data)
 
 void Communicator::sendMessage(const Message& message)
 {
-    if (!connected()) {
+    if (!isConnected()) {
         return;
     }
     const QString data = message.toString();
diff --git a/client/communicator.h b/client/communicator.h
index 8546bd59f..3c4f1628d 100644
--- a/client/communicator.h
+++ b/client/communicator.h
@@ -16,7 +16,7 @@ public:
     explicit Communicator(QObject* parent = nullptr);
     ~Communicator();
 
-    bool connected() const;
+    bool isConnected() const;
     void sendMessage(const Message& message);
 
 signals:
diff --git a/client/core/defs.h b/client/core/defs.h
index 83c75ff0e..99fc9e754 100644
--- a/client/core/defs.h
+++ b/client/core/defs.h
@@ -47,9 +47,13 @@ enum ErrorCode
     EasyRsaError,
 
     // Distro errors
-    AmneziaServiceConnectionFailed,
     OpenVpnExecutableMissing,
-    EasyRsaExecutableMissing
+    EasyRsaExecutableMissing,
+    AmneziaServiceConnectionFailed,
+
+    // VPN errors
+    OpenVpnAdaptersInUseError,
+    OpenVpnUnknownError
 };
 
 } // namespace amnezia
diff --git a/client/core/errorstrings.h b/client/core/errorstrings.h
index e3933ae69..0e9659121 100644
--- a/client/core/errorstrings.h
+++ b/client/core/errorstrings.h
@@ -31,12 +31,17 @@ QString errorString(ErrorCode code){
     // Local errors
     case (FailedToSaveConfigData): return QObject::tr("Failed to save config to disk");
     case (OpenVpnConfigMissing): return QObject::tr("OpenVPN config missing");
-    case (OpenVpnManagementServerError): return QObject::tr("OpenVpn management server error");
+    case (OpenVpnManagementServerError): return QObject::tr("OpenVPN management server error");
+    case (EasyRsaError): return QObject::tr("EasyRSA runtime error");
 
+    // Distro errors
     case (OpenVpnExecutableMissing): return QObject::tr("OpenVPN executable missing");
     case (EasyRsaExecutableMissing): return QObject::tr("EasyRsa executable missing");
     case (AmneziaServiceConnectionFailed): return QObject::tr("Amnezia helper service error");
 
+    // VPN errors
+    case (OpenVpnAdaptersInUseError): return QObject::tr("Can't connect: another VPN connection is active");
+
     case(InternalError):
     default:
         return QObject::tr("Internal error");
diff --git a/client/protocols/openvpnprotocol.cpp b/client/protocols/openvpnprotocol.cpp
index d4e92a049..19d25a757 100644
--- a/client/protocols/openvpnprotocol.cpp
+++ b/client/protocols/openvpnprotocol.cpp
@@ -119,7 +119,7 @@ ErrorCode OpenVpnProtocol::start()
     m_openVpnStateSigTermHandlerTimer.stop();
     stop();
 
-    if (communicator() && !communicator()->connected()) {
+    if (communicator() && !communicator()->isConnected()) {
         setLastError(ErrorCode::AmneziaServiceConnectionFailed);
         return lastError();
     }
@@ -213,6 +213,16 @@ void OpenVpnProtocol::onReadyReadDataFromManagementServer()
             }
         }
 
+        if (line.contains("FATAL")) {
+            if (line.contains("tap-windows6 adapters on this system are currently in use or disabled")) {
+                emit protocolError(ErrorCode::OpenVpnAdaptersInUseError);
+            }
+            else {
+                emit protocolError(ErrorCode::OpenVpnUnknownError);
+            }
+        }
+
+
         QByteArray data(line.toStdString().c_str());
         if (data.contains(">BYTECOUNT:")) {
             int beg = data.lastIndexOf(">BYTECOUNT:");
diff --git a/client/protocols/vpnprotocol.cpp b/client/protocols/vpnprotocol.cpp
index 5e9c35ba4..eb81e02f6 100644
--- a/client/protocols/vpnprotocol.cpp
+++ b/client/protocols/vpnprotocol.cpp
@@ -93,14 +93,14 @@ void VpnProtocol::setConnectionState(VpnProtocol::ConnectionState state)
 QString VpnProtocol::textConnectionState(ConnectionState connectionState)
 {
     switch (connectionState) {
-    case ConnectionState::Unknown: return "Unknown";
-    case ConnectionState::Disconnected: return "Disconnected";
-    case ConnectionState::Preparing: return "Preparing";
-    case ConnectionState::Connecting: return "Connecting";
-    case ConnectionState::Connected: return "Connected";
-    case ConnectionState::Disconnecting: return "Disconnecting";
-    case ConnectionState::TunnelReconnecting: return "TunnelReconnecting";
-    case ConnectionState::Error: return "Error";
+    case ConnectionState::Unknown: return tr("Unknown");
+    case ConnectionState::Disconnected: return tr("Disconnected");
+    case ConnectionState::Preparing: return tr("Preparing");
+    case ConnectionState::Connecting: return tr("Connecting");
+    case ConnectionState::Connected: return tr("Connected");
+    case ConnectionState::Disconnecting: return tr("Disconnecting");
+    case ConnectionState::TunnelReconnecting: return tr("TunnelReconnecting");
+    case ConnectionState::Error: return tr("Error");
     default:
         ;
     }
@@ -113,12 +113,12 @@ QString VpnProtocol::textConnectionState() const
     return textConnectionState(m_connectionState);
 }
 
-bool VpnProtocol::connected() const
+bool VpnProtocol::onConnected() const
 {
     return m_connectionState == ConnectionState::Connected;
 }
 
-bool VpnProtocol::disconnected() const
+bool VpnProtocol::onDisconnected() const
 {
     return m_connectionState == ConnectionState::Disconnected;
 }
diff --git a/client/protocols/vpnprotocol.h b/client/protocols/vpnprotocol.h
index 3472afdf8..fa1fc9a9a 100644
--- a/client/protocols/vpnprotocol.h
+++ b/client/protocols/vpnprotocol.h
@@ -25,8 +25,8 @@ public:
     static void initializeCommunicator(QObject* parent = nullptr);
 
 
-    virtual bool connected() const;
-    virtual bool disconnected() const;
+    virtual bool onConnected() const;
+    virtual bool onDisconnected() const;
     virtual ErrorCode start() = 0;
     virtual void stop() = 0;
 
@@ -39,6 +39,7 @@ signals:
     void bytesChanged(quint64 receivedBytes, quint64 sentBytes);
     void connectionStateChanged(VpnProtocol::ConnectionState state);
     void timeoutTimerEvent();
+    void protocolError(amnezia::ErrorCode e);
 
 protected slots:
     virtual void onTimeout();
diff --git a/client/ui/mainwindow.cpp b/client/ui/mainwindow.cpp
index db995c679..a4deede92 100644
--- a/client/ui/mainwindow.cpp
+++ b/client/ui/mainwindow.cpp
@@ -76,6 +76,7 @@ MainWindow::MainWindow(QWidget *parent) :
     m_vpnConnection = new VpnConnection(this);
     connect(m_vpnConnection, SIGNAL(bytesChanged(quint64, quint64)), this, SLOT(onBytesChanged(quint64, quint64)));
     connect(m_vpnConnection, SIGNAL(connectionStateChanged(VpnProtocol::ConnectionState)), this, SLOT(onConnectionStateChanged(VpnProtocol::ConnectionState)));
+    connect(m_vpnConnection, SIGNAL(vpnProtocolError(amnezia::ErrorCode)), this, SLOT(onVpnProtocolError(amnezia::ErrorCode)));
 
     onConnectionStateChanged(VpnProtocol::ConnectionState::Disconnected);
 
@@ -90,7 +91,7 @@ MainWindow::~MainWindow()
     for (int i = 0; i < 50; i++) {
         qApp->processEvents(QEventLoop::ExcludeUserInputEvents);
         QThread::msleep(100);
-        if (m_vpnConnection->disconnected()) {
+        if (m_vpnConnection->onDisconnected()) {
             break;
         }
     }
@@ -297,6 +298,11 @@ void MainWindow::onConnectionStateChanged(VpnProtocol::ConnectionState state)
     ui->pushButton_connect->setEnabled(pushButtonConnectEnabled);
 }
 
+void MainWindow::onVpnProtocolError(ErrorCode errorCode)
+{
+    QMessageBox::critical(this, APPLICATION_NAME, errorString(errorCode));
+}
+
 void MainWindow::onPushButtonConnectToggled(bool checked)
 {
     if (checked) {
diff --git a/client/ui/mainwindow.h b/client/ui/mainwindow.h
index 6d02c8626..de5889eef 100644
--- a/client/ui/mainwindow.h
+++ b/client/ui/mainwindow.h
@@ -34,6 +34,8 @@ public:
 private slots:
     void onBytesChanged(quint64 receivedBytes, quint64 sentBytes);
     void onConnectionStateChanged(VpnProtocol::ConnectionState state);
+    void onVpnProtocolError(amnezia::ErrorCode errorCode);
+
     void onPushButtonBackFromNewServerClicked(bool clicked);
     void onPushButtonBackFromSettingsClicked(bool clicked);
     void onPushButtonBackFromSitesClicked(bool clicked);
diff --git a/client/vpnconnection.cpp b/client/vpnconnection.cpp
index 1ed8f4449..ef75f4e91 100644
--- a/client/vpnconnection.cpp
+++ b/client/vpnconnection.cpp
@@ -69,7 +69,11 @@ ErrorCode VpnConnection::connectToVpn(const ServerCredentials &credentials, Prot
         if (e) {
             return e;
         }
+        if (m_vpnProtocol) {
+            disconnect(m_vpnProtocol.data(), &VpnProtocol::protocolError, this, &VpnConnection::vpnProtocolError);
+        }
         m_vpnProtocol.reset(new OpenVpnProtocol());
+        connect(m_vpnProtocol.data(), &VpnProtocol::protocolError, this, &VpnConnection::vpnProtocolError);
     }
     else if (protocol == Protocol::ShadowSocks) {
         return ErrorCode::NotImplementedError;
@@ -96,20 +100,20 @@ void VpnConnection::disconnectFromVpn()
     m_vpnProtocol.data()->stop();
 }
 
-bool VpnConnection::connected() const
+bool VpnConnection::onConnected() const
 {
     if (!m_vpnProtocol.data()) {
         return false;
     }
 
-    return m_vpnProtocol.data()->connected();
+    return m_vpnProtocol.data()->onConnected();
 }
 
-bool VpnConnection::disconnected() const
+bool VpnConnection::onDisconnected() const
 {
     if (!m_vpnProtocol.data()) {
         return true;
     }
 
-    return m_vpnProtocol.data()->disconnected();
+    return m_vpnProtocol.data()->onDisconnected();
 }
diff --git a/client/vpnconnection.h b/client/vpnconnection.h
index 0bf81851c..9eb58ab30 100644
--- a/client/vpnconnection.h
+++ b/client/vpnconnection.h
@@ -23,13 +23,14 @@ public:
     ErrorCode lastError() const;
     ErrorCode requestVpnConfig(const ServerCredentials &credentials, Protocol protocol);
     ErrorCode connectToVpn(const ServerCredentials &credentials, Protocol protocol = Protocol::Any);
-    bool connected() const;
-    bool disconnected() const;
+    bool onConnected() const;
+    bool onDisconnected() const;
     void disconnectFromVpn();
 
 signals:
     void bytesChanged(quint64 receivedBytes, quint64 sentBytes);
     void connectionStateChanged(VpnProtocol::ConnectionState state);
+    void vpnProtocolError(amnezia::ErrorCode error);
 
 protected slots:
     void onBytesChanged(quint64 receivedBytes, quint64 sentBytes);