diff --git a/src/librssguard/definitions/definitions.h b/src/librssguard/definitions/definitions.h
index 974cdb92e..0c1a0838a 100755
--- a/src/librssguard/definitions/definitions.h
+++ b/src/librssguard/definitions/definitions.h
@@ -83,6 +83,8 @@
 #define HTTP_HEADERS_AUTHORIZATION  "Authorization"
 #define HTTP_HEADERS_USER_AGENT     "User-Agent"
 
+#define LOGSEC_NETWORK              "network: "
+#define LOGSEC_ADBLOCK              "adblock: "
 #define LOGSEC_FEEDMODEL            "feed-model: "
 #define LOGSEC_FEEDDOWNLOADER       "feed-downloader: "
 #define LOGSEC_MESSAGEMODEL         "message-model: "
diff --git a/src/librssguard/miscellaneous/databasequeries.cpp b/src/librssguard/miscellaneous/databasequeries.cpp
index be70464df..1191f3a5a 100755
--- a/src/librssguard/miscellaneous/databasequeries.cpp
+++ b/src/librssguard/miscellaneous/databasequeries.cpp
@@ -1874,6 +1874,27 @@ bool DatabaseQueries::deleteGmailAccount(const QSqlDatabase& db, int account_id)
   return q.exec();
 }
 
+bool DatabaseQueries::storeNewGmailTokens(const QSqlDatabase& db, const QString& refresh_token, int account_id) {
+  QSqlQuery query(db);
+
+  query.prepare("UPDATE GmailAccounts "
+                "SET refresh_token = :refresh_token "
+                "WHERE id = :id;");
+  query.bindValue(QSL(":refresh_token"), refresh_token);
+  query.bindValue(QSL(":id"), account_id);
+
+  if (query.exec()) {
+    return true;
+  }
+  else {
+    qWarningNN << LOGSEC_GMAIL
+               << "Updating tokens in DB failed: '"
+               << query.lastError().text()
+               << "'.";
+    return false;
+  }
+}
+
 bool DatabaseQueries::deleteInoreaderAccount(const QSqlDatabase& db, int account_id) {
   QSqlQuery q(db);
 
diff --git a/src/librssguard/miscellaneous/databasequeries.h b/src/librssguard/miscellaneous/databasequeries.h
index d6666140c..c9b4d7d82 100644
--- a/src/librssguard/miscellaneous/databasequeries.h
+++ b/src/librssguard/miscellaneous/databasequeries.h
@@ -147,6 +147,7 @@ class DatabaseQueries {
     // Gmail account.
     static QStringList getAllRecipients(const QSqlDatabase& db, int account_id);
     static bool deleteGmailAccount(const QSqlDatabase& db, int account_id);
+    static bool storeNewGmailTokens(const QSqlDatabase& db, const QString& refresh_token, int account_id);
     static QList<ServiceRoot*> getGmailAccounts(const QSqlDatabase& db, bool* ok = nullptr);
     static bool overwriteGmailAccount(const QSqlDatabase& db, const QString& username, const QString& app_id,
                                       const QString& app_key, const QString& redirect_url, const QString& refresh_token,
diff --git a/src/librssguard/miscellaneous/settings.cpp b/src/librssguard/miscellaneous/settings.cpp
index e6521115b..fc23e03e0 100755
--- a/src/librssguard/miscellaneous/settings.cpp
+++ b/src/librssguard/miscellaneous/settings.cpp
@@ -398,7 +398,7 @@ QString Settings::pathName() const {
 }
 
 QSettings::Status Settings::checkSettings() {
-  qDebug("Syncing settings.");
+  qDebugNN << LOGSEC_CORE << "Syncing settings.";
   sync();
   return status();
 }
@@ -414,14 +414,17 @@ void Settings::finishRestoration(const QString& desired_settings_file_path) {
                                        BACKUP_NAME_SETTINGS + BACKUP_SUFFIX_SETTINGS;
 
   if (QFile::exists(backup_settings_file)) {
-    qWarning("Backup settings file '%s' was detected. Restoring it.", qPrintable(QDir::toNativeSeparators(backup_settings_file)));
+    qWarningNN << LOGSEC_CORE
+               << "Backup settings file"
+               << QUOTE_W_SPACE(QDir::toNativeSeparators(backup_settings_file))
+               << "was detected. Restoring it.";
 
     if (IOFactory::copyFile(backup_settings_file, desired_settings_file_path)) {
       QFile::remove(backup_settings_file);
-      qDebug("Settings file was restored successully.");
+      qDebugNN << LOGSEC_CORE << "Settings file was restored successully.";
     }
     else {
-      qCritical("Settings file was NOT restored due to error when copying the file.");
+      qCriticalNN << LOGSEC_CORE << "Settings file was NOT restored due to error when copying the file.";
     }
   }
 }
@@ -441,11 +444,16 @@ Settings* Settings::setupSettings(QObject* parent) {
 
   // Check if portable settings are available.
   if (properties.m_type == SettingsProperties::SettingsType::Portable) {
-    qDebug("Initializing settings in '%s' (portable way).", qPrintable(QDir::toNativeSeparators(properties.m_absoluteSettingsFileName)));
+    qDebugNN << LOGSEC_CORE
+             << "Initializing settings in"
+             << QUOTE_W_SPACE(QDir::toNativeSeparators(properties.m_absoluteSettingsFileName))
+             << "(portable way).";
   }
   else {
-    qDebug("Initializing settings in '%s' (non-portable way).",
-           qPrintable(QDir::toNativeSeparators(properties.m_absoluteSettingsFileName)));
+    qDebugNN << LOGSEC_CORE
+             << "Initializing settings in"
+             << QUOTE_W_SPACE(QDir::toNativeSeparators(properties.m_absoluteSettingsFileName))
+             << "(non-portable way).";
   }
 
   return new_settings;
diff --git a/src/librssguard/miscellaneous/skinfactory.cpp b/src/librssguard/miscellaneous/skinfactory.cpp
index ad94e5bf4..f90a4cd0d 100644
--- a/src/librssguard/miscellaneous/skinfactory.cpp
+++ b/src/librssguard/miscellaneous/skinfactory.cpp
@@ -13,6 +13,7 @@ SkinFactory::SkinFactory(QObject* parent) : QObject(parent) {}
 
 void SkinFactory::loadCurrentSkin() {
   QList<QString> skin_names_to_try;
+
   skin_names_to_try.append(selectedSkinName());
   skin_names_to_try.append(APP_SKIN_DEFAULT);
   bool skin_parsed;
@@ -28,15 +29,15 @@ void SkinFactory::loadCurrentSkin() {
 
       // Set this 'Skin' object as active one.
       m_currentSkin = skin_data;
-      qDebug("Skin '%s' loaded.", qPrintable(skin_name));
+      qDebugNN << LOGSEC_GUI << "Skin" << QUOTE_W_SPACE(skin_name) << "loaded.";
       return;
     }
     else {
-      qWarning("Failed to load skin '%s'.", qPrintable(skin_name));
+      qWarningNN << LOGSEC_GUI << "Failed to load skin" << QUOTE_W_SPACE_DOT(skin_name);
     }
   }
 
-  qCritical("Failed to load selected or default skin. Quitting!");
+  qCriticalNN << LOGSEC_GUI << "Failed to load selected or default skin. Quitting!";
 }
 
 void SkinFactory::loadSkinFromData(const Skin& skin) {
diff --git a/src/librssguard/miscellaneous/systemfactory.cpp b/src/librssguard/miscellaneous/systemfactory.cpp
index 72c138847..f86c2aff9 100644
--- a/src/librssguard/miscellaneous/systemfactory.cpp
+++ b/src/librssguard/miscellaneous/systemfactory.cpp
@@ -65,7 +65,7 @@ SystemFactory::AutoStartStatus SystemFactory::autoStartStatus() const {
 
   // No correct path was found.
   if (desktop_file_location.isEmpty()) {
-    qWarning("Searching for auto-start function status failed. HOME variable not found.");
+    qWarningNN << LOGSEC_GUI << "Searching for auto-start function status failed. HOME variable not found.";
     return AutoStartStatus::Unavailable;
   }
 
diff --git a/src/librssguard/miscellaneous/textfactory.cpp b/src/librssguard/miscellaneous/textfactory.cpp
index 5aa32fff0..7f7638f90 100755
--- a/src/librssguard/miscellaneous/textfactory.cpp
+++ b/src/librssguard/miscellaneous/textfactory.cpp
@@ -120,7 +120,7 @@ QString TextFactory::decrypt(const QString& text) {
 QString TextFactory::newline() {
 #if defined(Q_OS_WIN)
   return QSL("\r\n");
-#elif defined(Q_OS_MACOSOS)
+#elif defined(Q_OS_MACOS)
   return QSL("\r");
 #else
   return QSL("\n");
@@ -152,8 +152,10 @@ quint64 TextFactory::initializeSecretEncryptionKey() {
         IOFactory::writeFile(encryption_file_path, QString::number(s_encryptionKey).toLocal8Bit());
       }
       catch (ApplicationException& ex) {
-        qCritical("Failed to write newly generated encryption key to file, error '%s'. Now, your passwords won't be "
-                  "readable after you start this application again.", qPrintable(ex.message()));
+        qCriticalNN << LOGSEC_CORE
+                    << "Failed to write newly generated encryption key to file, error"
+                    << QUOTE_W_SPACE_DOT(ex.message())
+                    << " Now, your passwords won't be readable after you start this application again.";
       }
     }
   }
diff --git a/src/librssguard/network-web/adblock/adblockmanager.cpp b/src/librssguard/network-web/adblock/adblockmanager.cpp
index 35aeb3e3f..d13491801 100644
--- a/src/librssguard/network-web/adblock/adblockmanager.cpp
+++ b/src/librssguard/network-web/adblock/adblockmanager.cpp
@@ -174,7 +174,9 @@ AdBlockSubscription* AdBlockManager::addSubscription(const QString& title, const
   QSaveFile file(filePath);
 
   if (!file.open(QFile::WriteOnly)) {
-    qWarning("Cannot save AdBlock subscription to file '%s'.", qPrintable(filePath));
+    qWarningNN << LOGSEC_ADBLOCK
+               << "Cannot save AdBlock subscription to file"
+               << QUOTE_W_SPACE_DOT(filePath);
     return nullptr;
   }
 
@@ -262,7 +264,9 @@ void AdBlockManager::load() {
     QUrl url = QUrl(textStream.readLine(1024).remove(QLatin1String("Url: ")));
 
     if (title.isEmpty() || !url.isValid()) {
-      qWarning("Invalid AdBlock subscription file '%s'.", qPrintable(absolutePath));
+      qWarningNN << LOGSEC_ADBLOCK
+                 << "Invalid AdBlock subscription file"
+                 << QUOTE_W_SPACE_DOT(absolutePath);
       continue;
     }
 
diff --git a/src/librssguard/network-web/adblock/adblocksearchtree.cpp b/src/librssguard/network-web/adblock/adblocksearchtree.cpp
index 8a67dae92..29f0bf0b0 100644
--- a/src/librssguard/network-web/adblock/adblocksearchtree.cpp
+++ b/src/librssguard/network-web/adblock/adblocksearchtree.cpp
@@ -20,6 +20,8 @@
 #include "network-web/adblock/adblockrule.h"
 #include "network-web/adblock/adblocksearchtree.h"
 
+#include "definitions/definitions.h"
+
 #include <QWebEngineUrlRequestInfo>
 
 AdBlockSearchTree::AdBlockSearchTree() : m_root(new Node) {}
@@ -42,7 +44,7 @@ bool AdBlockSearchTree::add(const AdBlockRule* rule) {
   int len = filter.size();
 
   if (len <= 0) {
-    qDebug("AdBlockSearchTree: Inserting rule with filter len <= 0!");
+    qWarningNN << LOGSEC_ADBLOCK << "Inserting rule with filter len <= 0!";
     return false;
   }
 
diff --git a/src/librssguard/network-web/adblock/adblocksubscription.cpp b/src/librssguard/network-web/adblock/adblocksubscription.cpp
index 0964f90c4..b29c0e0d8 100644
--- a/src/librssguard/network-web/adblock/adblocksubscription.cpp
+++ b/src/librssguard/network-web/adblock/adblocksubscription.cpp
@@ -94,7 +94,10 @@ void AdBlockSubscription::loadSubscription(const QStringList& disabledRules) {
   }
 
   if (!file.open(QFile::ReadOnly)) {
-    qWarning("Unable to open adblock file '%s' for reading.", qPrintable(m_filePath));
+    qWarningNN << LOGSEC_ADBLOCK
+               << "Unable to open adblock file"
+               << QUOTE_W_SPACE(m_filePath)
+               << "for reading.";
     QTimer::singleShot(0, this, SLOT(updateSubscription()));
     return;
   }
@@ -109,7 +112,9 @@ void AdBlockSubscription::loadSubscription(const QStringList& disabledRules) {
   QString header = textStream.readLine(1024);
 
   if (!header.startsWith(QL1S("[Adblock")) || m_title.isEmpty()) {
-    qWarning("Invalid format of AdBlock file '%s'.", qPrintable(m_filePath));
+    qWarningNN << LOGSEC_ADBLOCK
+               << "Invalid format of AdBlock file"
+               << QUOTE_W_SPACE_DOT(m_filePath);
     QTimer::singleShot(0, this, SLOT(updateSubscription()));
     return;
   }
@@ -176,7 +181,10 @@ bool AdBlockSubscription::saveDownloadedData(const QByteArray& data) {
   QSaveFile file(m_filePath);
 
   if (!file.open(QFile::WriteOnly)) {
-    qWarning("Unable to open AdBlock file '%s' for writing.", qPrintable(m_filePath));
+    qWarningNN << LOGSEC_ADBLOCK
+               << "Unable to open AdBlock file"
+               << QUOTE_W_SPACE(m_filePath)
+               << "for writing.";
     return false;
   }
   else {
@@ -306,7 +314,10 @@ void AdBlockCustomList::saveSubscription() {
   QFile file(filePath());
 
   if (!file.open(QFile::ReadWrite | QFile::Truncate)) {
-    qWarning("Unable to open AdBlock file '%s' for writing.", qPrintable(filePath()));
+    qWarningNN << LOGSEC_ADBLOCK
+               << "Unable to open AdBlock file"
+               << QUOTE_W_SPACE(filePath())
+               << "for writing.";
     return;
   }
 
diff --git a/src/librssguard/network-web/basenetworkaccessmanager.cpp b/src/librssguard/network-web/basenetworkaccessmanager.cpp
index 89e0c6d1f..89e05ef06 100644
--- a/src/librssguard/network-web/basenetworkaccessmanager.cpp
+++ b/src/librssguard/network-web/basenetworkaccessmanager.cpp
@@ -29,12 +29,18 @@ void BaseNetworkAccessManager::loadSettings() {
     setProxy(QNetworkProxy::applicationProxy());
   }
 
-  qDebug("Settings of BaseNetworkAccessManager loaded.");
+  qDebugNN << LOGSEC_NETWORK << "Settings of BaseNetworkAccessManager loaded.";
 }
 
 void BaseNetworkAccessManager::onSslErrors(QNetworkReply* reply, const QList<QSslError>& error) {
-  qWarning("Ignoring SSL errors for '%s': '%s' (code %d).", qPrintable(reply->url().toString()), qPrintable(reply->errorString()),
-           int(reply->error()));
+  qWarningNN << LOGSEC_NETWORK
+             << "Ignoring SSL errors for '"
+             << reply->url().toString()
+             << "':"
+             << QUOTE_W_SPACE(reply->errorString())
+             << "(code "
+             << reply->error()
+             << ").";
   reply->ignoreSslErrors(error);
 }
 
@@ -45,7 +51,7 @@ QNetworkReply* BaseNetworkAccessManager::createRequest(QNetworkAccessManager::Op
 
   // This rapidly speeds up loading of web sites.
   // NOTE: https://en.wikipedia.org/wiki/HTTP_pipelining
-  new_request.setAttribute(QNetworkRequest::HttpPipeliningAllowedAttribute, true);
+  new_request.setAttribute(QNetworkRequest::Attribute::HttpPipeliningAllowedAttribute, true);
 
   // Setup custom user-agent.
   new_request.setRawHeader(HTTP_HEADERS_USER_AGENT, QString(APP_USERAGENT).toLocal8Bit());
diff --git a/src/librssguard/network-web/downloader.cpp b/src/librssguard/network-web/downloader.cpp
index d7ca09056..9cac5ea83 100644
--- a/src/librssguard/network-web/downloader.cpp
+++ b/src/librssguard/network-web/downloader.cpp
@@ -19,7 +19,9 @@ Downloader::Downloader(QObject* parent)
   connect(m_timer, &QTimer::timeout, this, &Downloader::cancel);
 }
 
-Downloader::~Downloader() = default;
+Downloader::~Downloader() {
+  qDebugNN << LOGSEC_NETWORK << "Destroying Downloader instance.";
+}
 
 void Downloader::downloadFile(const QString& url, int timeout, bool protected_contents, const QString& username,
                               const QString& password) {
@@ -67,7 +69,9 @@ void Downloader::manipulateData(const QString& url,
   m_timer->setInterval(timeout);
 
   if (non_const_url.startsWith(URI_SCHEME_FEED)) {
-    qDebug("Replacing URI schemes for '%s'.", qPrintable(non_const_url));
+    qDebugNN << LOGSEC_NETWORK
+             << "Replacing URI schemes for"
+             << QUOTE_W_SPACE_DOT(non_const_url);
     request.setUrl(non_const_url.replace(QRegularExpression(QString('^') + URI_SCHEME_FEED), QString(URI_SCHEME_HTTP)));
   }
   else {
diff --git a/src/librssguard/network-web/downloader.h b/src/librssguard/network-web/downloader.h
index 1669e193d..0a2a41f32 100644
--- a/src/librssguard/network-web/downloader.h
+++ b/src/librssguard/network-web/downloader.h
@@ -19,8 +19,6 @@ class Downloader : public QObject {
   Q_OBJECT
 
   public:
-
-    // Constructors and destructors.
     explicit Downloader(QObject* parent = nullptr);
     virtual ~Downloader();
 
@@ -81,10 +79,8 @@ class Downloader : public QObject {
 
   private:
     QNetworkReply* m_activeReply;
-
     QScopedPointer<SilentNetworkAccessManager> m_downloadManager;
     QTimer* m_timer;
-
     QHash<QByteArray, QByteArray> m_customHeaders;
     QByteArray m_inputData;
     QHttpMultiPart* m_inputMultipartData;
@@ -94,7 +90,6 @@ class Downloader : public QObject {
 
     // Response data.
     QByteArray m_lastOutputData;
-
     QList<HttpResponse> m_lastOutputMultipartData;
 
     QNetworkReply::NetworkError m_lastOutputError;
diff --git a/src/librssguard/services/gmail/definitions.h b/src/librssguard/services/gmail/definitions.h
index 3c5cee25c..61a0ddf1e 100644
--- a/src/librssguard/services/gmail/definitions.h
+++ b/src/librssguard/services/gmail/definitions.h
@@ -12,7 +12,7 @@
 #define GMAIL_API_GET_ATTACHMENT    "https://www.googleapis.com/gmail/v1/users/me/messages/%1/attachments/%2"
 #define GMAIL_API_LABELS_LIST       "https://www.googleapis.com/gmail/v1/users/me/labels"
 #define GMAIL_API_MSGS_LIST         "https://www.googleapis.com/gmail/v1/users/me/messages"
-#define GMAIL_API_BATCH             "https://www.googleapis.com/batch"
+#define GMAIL_API_BATCH             "https://www.googleapis.com/batch/gmail/v1"
 
 #define GMAIL_ATTACHMENT_SEP      "####"
 
diff --git a/src/librssguard/services/gmail/network/gmailnetworkfactory.cpp b/src/librssguard/services/gmail/network/gmailnetworkfactory.cpp
index 116570829..fffaab1f4 100644
--- a/src/librssguard/services/gmail/network/gmailnetworkfactory.cpp
+++ b/src/librssguard/services/gmail/network/gmailnetworkfactory.cpp
@@ -118,10 +118,11 @@ void GmailNetworkFactory::initializeOauth() {
   connect(m_oauth2, &OAuth2Service::authFailed, this, &GmailNetworkFactory::onAuthFailed);
   connect(m_oauth2, &OAuth2Service::tokensReceived, this, [this](QString access_token, QString refresh_token, int expires_in) {
     Q_UNUSED(expires_in)
+    Q_UNUSED(access_token)
 
-    if (m_service != nullptr && !access_token.isEmpty() && !refresh_token.isEmpty()) {
+    if (m_service != nullptr && !refresh_token.isEmpty()) {
       QSqlDatabase database = qApp->database()->connection(metaObject()->className());
-      DatabaseQueries::storeNewInoreaderTokens(database, refresh_token, m_service->accountId());
+      DatabaseQueries::storeNewGmailTokens(database, refresh_token, m_service->accountId());
 
       qApp->showGuiMessage(tr("Logged in successfully"),
                            tr("Your login to Gmail was authorized."),
diff --git a/src/librssguard/services/inoreader/network/inoreadernetworkfactory.cpp b/src/librssguard/services/inoreader/network/inoreadernetworkfactory.cpp
index 4e878f4ff..0d9f2fe8f 100644
--- a/src/librssguard/services/inoreader/network/inoreadernetworkfactory.cpp
+++ b/src/librssguard/services/inoreader/network/inoreadernetworkfactory.cpp
@@ -54,8 +54,9 @@ void InoreaderNetworkFactory::initializeOauth() {
   connect(m_oauth2, &OAuth2Service::authFailed, this, &InoreaderNetworkFactory::onAuthFailed);
   connect(m_oauth2, &OAuth2Service::tokensReceived, this, [this](QString access_token, QString refresh_token, int expires_in) {
     Q_UNUSED(expires_in)
+    Q_UNUSED(access_token)
 
-    if (m_service != nullptr && !access_token.isEmpty() && !refresh_token.isEmpty()) {
+    if (m_service != nullptr && !refresh_token.isEmpty()) {
       QSqlDatabase database = qApp->database()->connection(metaObject()->className());
       DatabaseQueries::storeNewInoreaderTokens(database, refresh_token, m_service->accountId());