diff --git a/launcher/JavaCommon.cpp b/launcher/JavaCommon.cpp
index 52cc868a..e29e2270 100644
--- a/launcher/JavaCommon.cpp
+++ b/launcher/JavaCommon.cpp
@@ -122,8 +122,7 @@ void JavaCommon::TestCheck::run()
         return;
     }
     checker.reset(new JavaChecker());
-    connect(checker.get(), SIGNAL(checkFinished(JavaCheckResult)), this,
-            SLOT(checkFinished(JavaCheckResult)));
+    connect(checker.get(), &JavaChecker::checkFinished, this, &JavaCommon::TestCheck::checkFinished);
     checker->m_path = m_path;
     checker->performCheck();
 }
@@ -137,8 +136,7 @@ void JavaCommon::TestCheck::checkFinished(JavaCheckResult result)
         return;
     }
     checker.reset(new JavaChecker());
-    connect(checker.get(), SIGNAL(checkFinished(JavaCheckResult)), this,
-            SLOT(checkFinishedWithArgs(JavaCheckResult)));
+    connect(checker.get(), &JavaChecker::checkFinished, this, &JavaCommon::TestCheck::checkFinishedWithArgs);
     checker->m_path = m_path;
     checker->m_args = m_args;
     checker->m_minMem = m_minMem;
diff --git a/launcher/LoggedProcess.cpp b/launcher/LoggedProcess.cpp
index c8d5c34e..d70f6d00 100644
--- a/launcher/LoggedProcess.cpp
+++ b/launcher/LoggedProcess.cpp
@@ -44,12 +44,8 @@ LoggedProcess::LoggedProcess(QObject *parent) : QProcess(parent)
     // QProcess has a strange interface... let's map a lot of those into a few.
     connect(this, &QProcess::readyReadStandardOutput, this, &LoggedProcess::on_stdOut);
     connect(this, &QProcess::readyReadStandardError, this, &LoggedProcess::on_stdErr);
-    connect(this, SIGNAL(finished(int,QProcess::ExitStatus)), SLOT(on_exit(int,QProcess::ExitStatus)));
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    connect(this, SIGNAL(errorOccurred(QProcess::ProcessError)), this, SLOT(on_error(QProcess::ProcessError)));
-#else
-    connect(this, SIGNAL(error(QProcess::ProcessError)), this, SLOT(on_error(QProcess::ProcessError)));
-#endif
+    connect(this, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), this, &LoggedProcess::on_exit);
+    connect(this, &QProcess::errorOccurred, this, &LoggedProcess::on_error);
     connect(this, &QProcess::stateChanged, this, &LoggedProcess::on_stateChange);
 }
 
diff --git a/launcher/icons/IconList.cpp b/launcher/icons/IconList.cpp
index 1dfc6432..13174f6e 100644
--- a/launcher/icons/IconList.cpp
+++ b/launcher/icons/IconList.cpp
@@ -66,9 +66,8 @@ IconList::IconList(const QStringList &builtinPaths, QString path, QObject *paren
 
     m_watcher.reset(new QFileSystemWatcher());
     is_watching = false;
-    connect(m_watcher.get(), SIGNAL(directoryChanged(QString)),
-            SLOT(directoryChanged(QString)));
-    connect(m_watcher.get(), SIGNAL(fileChanged(QString)), SLOT(fileChanged(QString)));
+    connect(m_watcher.get(), &QFileSystemWatcher::directoryChanged, this, &IconList::directoryChanged);
+    connect(m_watcher.get(), &QFileSystemWatcher::fileChanged, this, &IconList::fileChanged);
 
     directoryChanged(path);
 
diff --git a/launcher/java/JavaChecker.cpp b/launcher/java/JavaChecker.cpp
index 041583d1..b4c55b3d 100644
--- a/launcher/java/JavaChecker.cpp
+++ b/launcher/java/JavaChecker.cpp
@@ -87,15 +87,11 @@ void JavaChecker::performCheck()
     process->setProcessEnvironment(CleanEnviroment());
     qDebug() << "Running java checker: " + m_path + args.join(" ");;
 
-    connect(process.get(), SIGNAL(finished(int, QProcess::ExitStatus)), this, SLOT(finished(int, QProcess::ExitStatus)));
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    connect(process.get(), SIGNAL(errorOccurred(QProcess::ProcessError)), this, SLOT(error(QProcess::ProcessError)));
-#else
-    connect(process.get(), SIGNAL(error(QProcess::ProcessError)), this, SLOT(error(QProcess::ProcessError)));
-#endif
-    connect(process.get(), SIGNAL(readyReadStandardOutput()), this, SLOT(stdoutReady()));
-    connect(process.get(), SIGNAL(readyReadStandardError()), this, SLOT(stderrReady()));
-    connect(&killTimer, SIGNAL(timeout()), SLOT(timeout()));
+    connect(process.get(), QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), this, &JavaChecker::finished);
+    connect(process.get(), &QProcess::errorOccurred, this, &JavaChecker::error);
+    connect(process.get(), &QProcess::readyReadStandardOutput, this, &JavaChecker::stdoutReady);
+    connect(process.get(), &QProcess::readyReadStandardError, this, &JavaChecker::stderrReady);
+    connect(&killTimer, &QTimer::timeout, this, &JavaChecker::timeout);
     killTimer.setSingleShot(true);
     killTimer.start(15000);
     process->start();
diff --git a/launcher/java/JavaCheckerJob.cpp b/launcher/java/JavaCheckerJob.cpp
index 67d70066..48274974 100644
--- a/launcher/java/JavaCheckerJob.cpp
+++ b/launcher/java/JavaCheckerJob.cpp
@@ -38,7 +38,7 @@ void JavaCheckerJob::executeTask()
     for (auto iter : javacheckers)
     {
         javaresults.append(JavaCheckResult());
-        connect(iter.get(), SIGNAL(checkFinished(JavaCheckResult)), SLOT(partFinished(JavaCheckResult)));
+        connect(iter.get(), &JavaChecker::checkFinished, this, &JavaCheckerJob::partFinished);
         iter->performCheck();
     }
 }
diff --git a/launcher/launch/steps/Update.cpp b/launcher/launch/steps/Update.cpp
index c8e576a5..77c8a18e 100644
--- a/launcher/launch/steps/Update.cpp
+++ b/launcher/launch/steps/Update.cpp
@@ -26,7 +26,7 @@ void Update::executeTask()
     m_updateTask.reset(m_parent->instance()->createUpdateTask(m_mode));
     if(m_updateTask)
     {
-        connect(m_updateTask.get(), SIGNAL(finished()), this, SLOT(updateFinished()));
+        connect(m_updateTask.get(), &Task::finished, this, &Update::updateFinished);
         connect(m_updateTask.get(), &Task::progress, this, &Update::setProgress);
         connect(m_updateTask.get(), &Task::stepProgress, this, &Update::propogateStepProgress);
         connect(m_updateTask.get(), &Task::status, this, &Update::setStatus);
diff --git a/launcher/minecraft/WorldList.cpp b/launcher/minecraft/WorldList.cpp
index 62e55cd4..df6b4ecc 100644
--- a/launcher/minecraft/WorldList.cpp
+++ b/launcher/minecraft/WorldList.cpp
@@ -53,8 +53,7 @@ WorldList::WorldList(const QString &dir, std::shared_ptr<const BaseInstance> ins
     m_dir.setSorting(QDir::Name | QDir::IgnoreCase | QDir::LocaleAware);
     m_watcher = new QFileSystemWatcher(this);
     is_watching = false;
-    connect(m_watcher, SIGNAL(directoryChanged(QString)), this,
-            SLOT(directoryChanged(QString)));
+    connect(m_watcher, &QFileSystemWatcher::directoryChanged, this, &WorldList::directoryChanged);
 }
 
 void WorldList::startWatching()
diff --git a/launcher/minecraft/auth/AuthRequest.cpp b/launcher/minecraft/auth/AuthRequest.cpp
index bb82e1e2..a21634b7 100644
--- a/launcher/minecraft/auth/AuthRequest.cpp
+++ b/launcher/minecraft/auth/AuthRequest.cpp
@@ -55,12 +55,12 @@ void AuthRequest::get(const QNetworkRequest &req, int timeout/* = 60*1000*/) {
     reply_ = APPLICATION->network()->get(request_);
     status_ = Requesting;
     timedReplies_.add(new Katabasis::Reply(reply_, timeout));
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    connect(reply_, SIGNAL(errorOccurred(QNetworkReply::NetworkError)), this, SLOT(onRequestError(QNetworkReply::NetworkError)));
-#else
-    connect(reply_, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(onRequestError(QNetworkReply::NetworkError)));
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) // QNetworkReply::errorOccurred added in 5.15
+    connect(reply_, &QNetworkReply::errorOccurred, this, &AuthRequest::onRequestError);
+#else // &QNetworkReply::error SIGNAL depricated
+    connect(reply_, QOverload<QNetworkReply::NetworkError>::of(&QNetworkReply::error), this, &AuthRequest::onRequestError);
 #endif
-    connect(reply_, SIGNAL(finished()), this, SLOT(onRequestFinished()));
+    connect(reply_, &QNetworkReply::finished, this, &AuthRequest::onRequestFinished);
     connect(reply_, &QNetworkReply::sslErrors, this, &AuthRequest::onSslErrors);
 }
 
@@ -70,14 +70,14 @@ void AuthRequest::post(const QNetworkRequest &req, const QByteArray &data, int t
     status_ = Requesting;
     reply_ = APPLICATION->network()->post(request_, data_);
     timedReplies_.add(new Katabasis::Reply(reply_, timeout));
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    connect(reply_, SIGNAL(errorOccurred(QNetworkReply::NetworkError)), this, SLOT(onRequestError(QNetworkReply::NetworkError)));
-#else
-    connect(reply_, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(onRequestError(QNetworkReply::NetworkError)));
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) // QNetworkReply::errorOccurred added in 5.15
+    connect(reply_, &QNetworkReply::errorOccurred, this, &AuthRequest::onRequestError);
+#else // &QNetworkReply::error SIGNAL depricated
+    connect(reply_, QOverload<QNetworkReply::NetworkError>::of(&QNetworkReply::error), this, &AuthRequest::onRequestError);
 #endif
-    connect(reply_, SIGNAL(finished()), this, SLOT(onRequestFinished()));
+    connect(reply_, &QNetworkReply::finished, this, &AuthRequest::onRequestFinished);
     connect(reply_, &QNetworkReply::sslErrors, this, &AuthRequest::onSslErrors);
-    connect(reply_, SIGNAL(uploadProgress(qint64,qint64)), this, SLOT(onUploadProgress(qint64,qint64)));
+    connect(reply_, &QNetworkReply::uploadProgress, this, &AuthRequest::onUploadProgress);
 }
 
 void AuthRequest::onRequestFinished() {
diff --git a/launcher/minecraft/auth/MinecraftAccount.cpp b/launcher/minecraft/auth/MinecraftAccount.cpp
index 48cf5d42..3b050ac0 100644
--- a/launcher/minecraft/auth/MinecraftAccount.cpp
+++ b/launcher/minecraft/auth/MinecraftAccount.cpp
@@ -133,8 +133,8 @@ shared_qobject_ptr<AccountTask> MinecraftAccount::login(QString password) {
     Q_ASSERT(m_currentTask.get() == nullptr);
 
     m_currentTask.reset(new MojangLogin(&data, password));
-    connect(m_currentTask.get(), SIGNAL(succeeded()), SLOT(authSucceeded()));
-    connect(m_currentTask.get(), SIGNAL(failed(QString)), SLOT(authFailed(QString)));
+    connect(m_currentTask.get(), &Task::succeeded, this, &MinecraftAccount::authSucceeded);
+    connect(m_currentTask.get(), &Task::failed, this, &MinecraftAccount::authFailed);
     connect(m_currentTask.get(), &Task::aborted, this, [this]{ authFailed(tr("Aborted")); });
     emit activityChanged(true);
     return m_currentTask;
@@ -144,8 +144,8 @@ shared_qobject_ptr<AccountTask> MinecraftAccount::loginMSA() {
     Q_ASSERT(m_currentTask.get() == nullptr);
 
     m_currentTask.reset(new MSAInteractive(&data));
-    connect(m_currentTask.get(), SIGNAL(succeeded()), SLOT(authSucceeded()));
-    connect(m_currentTask.get(), SIGNAL(failed(QString)), SLOT(authFailed(QString)));
+    connect(m_currentTask.get(), &Task::succeeded, this, &MinecraftAccount::authSucceeded);
+    connect(m_currentTask.get(), &Task::failed, this, &MinecraftAccount::authFailed);
     connect(m_currentTask.get(), &Task::aborted, this, [this]{ authFailed(tr("Aborted")); });
     emit activityChanged(true);
     return m_currentTask;
@@ -155,8 +155,8 @@ shared_qobject_ptr<AccountTask> MinecraftAccount::loginOffline() {
     Q_ASSERT(m_currentTask.get() == nullptr);
 
     m_currentTask.reset(new OfflineLogin(&data));
-    connect(m_currentTask.get(), SIGNAL(succeeded()), SLOT(authSucceeded()));
-    connect(m_currentTask.get(), SIGNAL(failed(QString)), SLOT(authFailed(QString)));
+    connect(m_currentTask.get(), &Task::succeeded, this, &MinecraftAccount::authSucceeded);
+    connect(m_currentTask.get(), &Task::failed, this, &MinecraftAccount::authFailed);
     connect(m_currentTask.get(), &Task::aborted, this, [this]{ authFailed(tr("Aborted")); });
     emit activityChanged(true);
     return m_currentTask;
@@ -177,8 +177,8 @@ shared_qobject_ptr<AccountTask> MinecraftAccount::refresh() {
         m_currentTask.reset(new MojangRefresh(&data));
     }
 
-    connect(m_currentTask.get(), SIGNAL(succeeded()), SLOT(authSucceeded()));
-    connect(m_currentTask.get(), SIGNAL(failed(QString)), SLOT(authFailed(QString)));
+    connect(m_currentTask.get(), &Task::succeeded, this, &MinecraftAccount::authSucceeded);
+    connect(m_currentTask.get(), &Task::failed, this, &MinecraftAccount::authFailed);
     connect(m_currentTask.get(), &Task::aborted, this, [this]{ authFailed(tr("Aborted")); });
     emit activityChanged(true);
     return m_currentTask;
diff --git a/launcher/minecraft/auth/steps/XboxUserStep.cpp b/launcher/minecraft/auth/steps/XboxUserStep.cpp
index 53069597..842eb60f 100644
--- a/launcher/minecraft/auth/steps/XboxUserStep.cpp
+++ b/launcher/minecraft/auth/steps/XboxUserStep.cpp
@@ -38,6 +38,10 @@ void XboxUserStep::perform() {
     QNetworkRequest request = QNetworkRequest(QUrl("https://user.auth.xboxlive.com/user/authenticate"));
     request.setHeader(QNetworkRequest::ContentTypeHeader, "application/json");
     request.setRawHeader("Accept", "application/json");
+    // set contract-verison header (prevent err 400 bad-request?)
+    // https://learn.microsoft.com/en-us/gaming/gdk/_content/gc/reference/live/rest/additional/httpstandardheaders
+    request.setRawHeader("x-xbl-contract-version", "1"); 
+
     auto *requestor = new AuthRequest(this);
     connect(requestor, &AuthRequest::finished, this, &XboxUserStep::onRequestDone);
     requestor->post(request, xbox_auth_data.toUtf8());
diff --git a/launcher/minecraft/services/CapeChange.cpp b/launcher/minecraft/services/CapeChange.cpp
index c73a11b6..1d5ea36d 100644
--- a/launcher/minecraft/services/CapeChange.cpp
+++ b/launcher/minecraft/services/CapeChange.cpp
@@ -54,9 +54,14 @@ void CapeChange::setCape(QString& cape) {
     setStatus(tr("Equipping cape"));
 
     m_reply = shared_qobject_ptr<QNetworkReply>(rep);
-    connect(rep, &QNetworkReply::uploadProgress, this, &Task::setProgress);
-    connect(rep, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(downloadError(QNetworkReply::NetworkError)));
-    connect(rep, SIGNAL(finished()), this, SLOT(downloadFinished()));
+    connect(rep, &QNetworkReply::uploadProgress, this, &CapeChange::setProgress);
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) // QNetworkReply::errorOccurred added in 5.15
+    connect(rep, &QNetworkReply::errorOccurred, this, &CapeChange::downloadError);
+#else
+    connect(rep, QOverload<QNetworkReply::NetworkError>::of(&QNetworkReply::error), this, &CapeChange::downloadError);
+#endif
+    connect(rep, &QNetworkReply::sslErrors, this, &CapeChange::sslErrors);
+    connect(rep, &QNetworkReply::finished, this, &CapeChange::downloadFinished);
 }
 
 void CapeChange::clearCape() {
@@ -68,13 +73,14 @@ void CapeChange::clearCape() {
     setStatus(tr("Removing cape"));
 
     m_reply = shared_qobject_ptr<QNetworkReply>(rep);
-    connect(rep, &QNetworkReply::uploadProgress, this, &Task::setProgress);
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    connect(rep, SIGNAL(errorOccurred(QNetworkReply::NetworkError)), this, SLOT(downloadError(QNetworkReply::NetworkError)));
+    connect(rep, &QNetworkReply::uploadProgress, this, &CapeChange::setProgress);
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) // QNetworkReply::errorOccurred added in 5.15
+    connect(rep, &QNetworkReply::errorOccurred, this, &CapeChange::downloadError);
 #else
-    connect(rep, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(downloadError(QNetworkReply::NetworkError)));
+    connect(rep, QOverload<QNetworkReply::NetworkError>::of(&QNetworkReply::error), this, &CapeChange::downloadError);
 #endif
-    connect(rep, SIGNAL(finished()), this, SLOT(downloadFinished()));
+    connect(rep, &QNetworkReply::sslErrors, this, &CapeChange::sslErrors);
+    connect(rep, &QNetworkReply::finished, this, &CapeChange::downloadFinished);
 }
 
 
@@ -95,6 +101,17 @@ void CapeChange::downloadError(QNetworkReply::NetworkError error)
     emitFailed(m_reply->errorString());
 }
 
+void CapeChange::sslErrors(const QList<QSslError>& errors)
+{
+    int i = 1;
+    for (auto error : errors) {
+        qCritical() << "Cape change SSL Error #" << i << " : " << error.errorString();
+        auto cert = error.certificate();
+        qCritical() << "Certificate in question:\n" << cert.toText();
+        i++;
+    }
+}
+
 void CapeChange::downloadFinished()
 {
     // if the download failed
diff --git a/launcher/minecraft/services/CapeChange.h b/launcher/minecraft/services/CapeChange.h
index 185d69b6..38069f90 100644
--- a/launcher/minecraft/services/CapeChange.h
+++ b/launcher/minecraft/services/CapeChange.h
@@ -27,6 +27,7 @@ protected:
 
 public slots:
     void downloadError(QNetworkReply::NetworkError);
+    void sslErrors(const QList<QSslError>& errors);
     void downloadFinished();
 };
 
diff --git a/launcher/minecraft/services/SkinDelete.cpp b/launcher/minecraft/services/SkinDelete.cpp
index 921bd094..fbaaeacb 100644
--- a/launcher/minecraft/services/SkinDelete.cpp
+++ b/launcher/minecraft/services/SkinDelete.cpp
@@ -53,13 +53,14 @@ void SkinDelete::executeTask()
     m_reply = shared_qobject_ptr<QNetworkReply>(rep);
 
     setStatus(tr("Deleting skin"));
-    connect(rep, &QNetworkReply::uploadProgress, this, &Task::setProgress);
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    connect(rep, SIGNAL(errorOccurred(QNetworkReply::NetworkError)), this, SLOT(downloadError(QNetworkReply::NetworkError)));
+    connect(rep, &QNetworkReply::uploadProgress, this, &SkinDelete::setProgress);
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) // QNetworkReply::errorOccurred added in 5.15
+    connect(rep, &QNetworkReply::errorOccurred, this, &SkinDelete::downloadError);
 #else
-    connect(rep, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(downloadError(QNetworkReply::NetworkError)));
+    connect(rep, QOverload<QNetworkReply::NetworkError>::of(&QNetworkReply::error), this, &SkinDelete::downloadError);
 #endif
-    connect(rep, SIGNAL(finished()), this, SLOT(downloadFinished()));
+    connect(rep, &QNetworkReply::sslErrors, this, &SkinDelete::sslErrors);
+    connect(rep, &QNetworkReply::finished, this, &SkinDelete::downloadFinished);
 }
 
 void SkinDelete::downloadError(QNetworkReply::NetworkError error)
@@ -69,6 +70,17 @@ void SkinDelete::downloadError(QNetworkReply::NetworkError error)
     emitFailed(m_reply->errorString());
 }
 
+void SkinDelete::sslErrors(const QList<QSslError>& errors)
+{
+    int i = 1;
+    for (auto error : errors) {
+        qCritical() << "Skin Delete SSL Error #" << i << " : " << error.errorString();
+        auto cert = error.certificate();
+        qCritical() << "Certificate in question:\n" << cert.toText();
+        i++;
+    }
+}
+
 void SkinDelete::downloadFinished()
 {
     // if the download failed
diff --git a/launcher/minecraft/services/SkinDelete.h b/launcher/minecraft/services/SkinDelete.h
index 83a84685..b9a1c9d3 100644
--- a/launcher/minecraft/services/SkinDelete.h
+++ b/launcher/minecraft/services/SkinDelete.h
@@ -22,5 +22,6 @@ protected:
 
 public slots:
     void downloadError(QNetworkReply::NetworkError);
+    void sslErrors(const QList<QSslError>& errors);
     void downloadFinished();
 };
diff --git a/launcher/minecraft/services/SkinUpload.cpp b/launcher/minecraft/services/SkinUpload.cpp
index c7987875..711f8739 100644
--- a/launcher/minecraft/services/SkinUpload.cpp
+++ b/launcher/minecraft/services/SkinUpload.cpp
@@ -78,13 +78,14 @@ void SkinUpload::executeTask()
     m_reply = shared_qobject_ptr<QNetworkReply>(rep);
 
     setStatus(tr("Uploading skin"));
-    connect(rep, &QNetworkReply::uploadProgress, this, &Task::setProgress);
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    connect(rep, SIGNAL(errorOccurred(QNetworkReply::NetworkError)), this, SLOT(downloadError(QNetworkReply::NetworkError)));
+    connect(rep, &QNetworkReply::uploadProgress, this, &SkinUpload::setProgress);
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) // QNetworkReply::errorOccurred added in 5.15
+    connect(rep, &QNetworkReply::errorOccurred, this, &SkinUpload::downloadError);
 #else
-    connect(rep, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(downloadError(QNetworkReply::NetworkError)));
+    connect(rep, QOverload<QNetworkReply::NetworkError>::of(&QNetworkReply::error), this, &SkinUpload::downloadError);
 #endif
-    connect(rep, SIGNAL(finished()), this, SLOT(downloadFinished()));
+    connect(rep, &QNetworkReply::sslErrors, this, &SkinUpload::sslErrors);
+    connect(rep, &QNetworkReply::finished, this, &SkinUpload::downloadFinished);
 }
 
 void SkinUpload::downloadError(QNetworkReply::NetworkError error)
@@ -94,6 +95,17 @@ void SkinUpload::downloadError(QNetworkReply::NetworkError error)
     emitFailed(m_reply->errorString());
 }
 
+void SkinUpload::sslErrors(const QList<QSslError>& errors)
+{
+    int i = 1;
+    for (auto error : errors) {
+        qCritical() << "Skin Upload SSL Error #" << i << " : " << error.errorString();
+        auto cert = error.certificate();
+        qCritical() << "Certificate in question:\n" << cert.toText();
+        i++;
+    }
+}
+
 void SkinUpload::downloadFinished()
 {
     // if the download failed
diff --git a/launcher/minecraft/services/SkinUpload.h b/launcher/minecraft/services/SkinUpload.h
index 2c1f0a2e..ac8c5b36 100644
--- a/launcher/minecraft/services/SkinUpload.h
+++ b/launcher/minecraft/services/SkinUpload.h
@@ -32,6 +32,7 @@ protected:
 public slots:
 
     void downloadError(QNetworkReply::NetworkError);
+    void sslErrors(const QList<QSslError>& errors);
 
     void downloadFinished();
 };
diff --git a/launcher/net/Download.cpp b/launcher/net/Download.cpp
index 7617b5a0..cd3fcc85 100644
--- a/launcher/net/Download.cpp
+++ b/launcher/net/Download.cpp
@@ -142,10 +142,10 @@ void Download::executeTask()
     m_reply.reset(rep);
     connect(rep, &QNetworkReply::downloadProgress, this, &Download::downloadProgress);
     connect(rep, &QNetworkReply::finished, this, &Download::downloadFinished);
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    connect(rep, SIGNAL(errorOccurred(QNetworkReply::NetworkError)), SLOT(downloadError(QNetworkReply::NetworkError)));
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) // QNetworkReply::errorOccurred added in 5.15
+    connect(rep, &QNetworkReply::errorOccurred, this, &Download::downloadError);
 #else
-    connect(rep, SIGNAL(error(QNetworkReply::NetworkError)), SLOT(downloadError(QNetworkReply::NetworkError)));
+    connect(rep, QOverload<QNetworkReply::NetworkError>::of(&QNetworkReply::error), this, &Download::downloadError);
 #endif
     connect(rep, &QNetworkReply::sslErrors, this, &Download::sslErrors);
     connect(rep, &QNetworkReply::readyRead, this, &Download::downloadReadyRead);
diff --git a/launcher/net/Download.h b/launcher/net/Download.h
index d8c18319..920164a3 100644
--- a/launcher/net/Download.h
+++ b/launcher/net/Download.h
@@ -74,7 +74,7 @@ class Download : public NetAction {
    protected slots:
     void downloadProgress(qint64 bytesReceived, qint64 bytesTotal) override;
     void downloadError(QNetworkReply::NetworkError error) override;
-    void sslErrors(const QList<QSslError>& errors);
+    void sslErrors(const QList<QSslError>& errors) override;
     void downloadFinished() override;
     void downloadReadyRead() override;
 
diff --git a/launcher/net/HttpMetaCache.cpp b/launcher/net/HttpMetaCache.cpp
index e521c9e9..689dbac9 100644
--- a/launcher/net/HttpMetaCache.cpp
+++ b/launcher/net/HttpMetaCache.cpp
@@ -57,7 +57,7 @@ HttpMetaCache::HttpMetaCache(QString path) : QObject(), m_index_file(path)
     saveBatchingTimer.setSingleShot(true);
     saveBatchingTimer.setTimerType(Qt::VeryCoarseTimer);
 
-    connect(&saveBatchingTimer, SIGNAL(timeout()), SLOT(SaveNow()));
+    connect(&saveBatchingTimer, &QTimer::timeout, this, &HttpMetaCache::SaveNow);
 }
 
 HttpMetaCache::~HttpMetaCache()
diff --git a/launcher/net/NetAction.h b/launcher/net/NetAction.h
index 32095041..ab9322c2 100644
--- a/launcher/net/NetAction.h
+++ b/launcher/net/NetAction.h
@@ -62,6 +62,17 @@ class NetAction : public Task {
     virtual void downloadFinished() = 0;
     virtual void downloadReadyRead() = 0;
 
+    virtual void sslErrors(const QList<QSslError>& errors) {
+        int i = 1;
+        for (auto error : errors) {
+            qCritical() << "Network SSL Error #" << i << " : " << error.errorString();
+            auto cert = error.certificate();
+            qCritical() << "Certificate in question:\n" << cert.toText();
+            i++;
+        }
+
+    };
+
    public slots:
     void startAction(shared_qobject_ptr<QNetworkAccessManager> network)
     {
diff --git a/launcher/net/Upload.cpp b/launcher/net/Upload.cpp
index 8045f850..4f9553ed 100644
--- a/launcher/net/Upload.cpp
+++ b/launcher/net/Upload.cpp
@@ -235,9 +235,13 @@ namespace Net {
         QNetworkReply* rep = m_network->post(request, m_post_data);
 
         m_reply.reset(rep);
-        connect(rep, SIGNAL(downloadProgress(qint64, qint64)), SLOT(downloadProgress(qint64, qint64)));
-        connect(rep, SIGNAL(finished()), SLOT(downloadFinished()));
-        connect(rep, SIGNAL(error(QNetworkReply::NetworkError)), SLOT(downloadError(QNetworkReply::NetworkError)));
+        connect(rep, &QNetworkReply::downloadProgress, this,  &Upload::downloadProgress);
+        connect(rep, &QNetworkReply::finished, this, &Upload::downloadFinished);
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) // QNetworkReply::errorOccurred added in 5.15
+        connect(rep, &QNetworkReply::errorOccurred, this, &Upload::downloadError);
+#else
+        connect(rep, QOverload<QNetworkReply::NetworkError>::of(&QNetworkReply::error), this, &Upload::downloadError);
+#endif
         connect(rep, &QNetworkReply::sslErrors, this, &Upload::sslErrors);
         connect(rep, &QNetworkReply::readyRead, this, &Upload::downloadReadyRead);
     }
diff --git a/launcher/net/Upload.h b/launcher/net/Upload.h
index 5182ab09..e8f0ea40 100644
--- a/launcher/net/Upload.h
+++ b/launcher/net/Upload.h
@@ -55,7 +55,7 @@ namespace Net {
     protected slots:
         void downloadProgress(qint64 bytesReceived, qint64 bytesTotal) override;
         void downloadError(QNetworkReply::NetworkError error) override;
-        void sslErrors(const QList<QSslError> & errors);
+        void sslErrors(const QList<QSslError> & errors) override;
         void downloadFinished() override;
         void downloadReadyRead() override;
 
diff --git a/launcher/screenshots/ImgurAlbumCreation.cpp b/launcher/screenshots/ImgurAlbumCreation.cpp
index a72c32d3..ab425f1a 100644
--- a/launcher/screenshots/ImgurAlbumCreation.cpp
+++ b/launcher/screenshots/ImgurAlbumCreation.cpp
@@ -74,17 +74,20 @@ void ImgurAlbumCreation::executeTask()
     m_reply.reset(rep);
     connect(rep, &QNetworkReply::uploadProgress, this, &ImgurAlbumCreation::downloadProgress);
     connect(rep, &QNetworkReply::finished, this, &ImgurAlbumCreation::downloadFinished);
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    connect(rep, SIGNAL(errorOccurred(QNetworkReply::NetworkError)), SLOT(downloadError(QNetworkReply::NetworkError)));
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) // QNetworkReply::errorOccurred added in 5.15
+    connect(rep, &QNetworkReply::errorOccurred, this, &ImgurAlbumCreation::downloadError);
 #else
-    connect(rep, SIGNAL(error(QNetworkReply::NetworkError)), SLOT(downloadError(QNetworkReply::NetworkError)));
+    connect(rep, QOverload<QNetworkReply::NetworkError>::of(&QNetworkReply::error), this, &ImgurAlbumCreation::downloadError);
 #endif
+    connect(rep, &QNetworkReply::sslErrors, this, &ImgurAlbumCreation::sslErrors);
 }
+
 void ImgurAlbumCreation::downloadError(QNetworkReply::NetworkError error)
 {
     qDebug() << m_reply->errorString();
     m_state = State::Failed;
 }
+
 void ImgurAlbumCreation::downloadFinished()
 {
     if (m_state != State::Failed)
@@ -120,6 +123,7 @@ void ImgurAlbumCreation::downloadFinished()
         return;
     }
 }
+
 void ImgurAlbumCreation::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
 {
     setProgress(bytesReceived, bytesTotal);
diff --git a/launcher/screenshots/ImgurUpload.cpp b/launcher/screenshots/ImgurUpload.cpp
index f8ac9bc2..a50f9afa 100644
--- a/launcher/screenshots/ImgurUpload.cpp
+++ b/launcher/screenshots/ImgurUpload.cpp
@@ -89,12 +89,14 @@ void ImgurUpload::executeTask()
     m_reply.reset(rep);
     connect(rep, &QNetworkReply::uploadProgress, this, &ImgurUpload::downloadProgress);
     connect(rep, &QNetworkReply::finished, this, &ImgurUpload::downloadFinished);
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    connect(rep, SIGNAL(errorOccurred(QNetworkReply::NetworkError)), SLOT(downloadError(QNetworkReply::NetworkError)));
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) // QNetworkReply::errorOccurred added in 5.15
+    connect(rep, &QNetworkReply::errorOccurred, this, &ImgurUpload::downloadError);
 #else
-    connect(rep, SIGNAL(error(QNetworkReply::NetworkError)), SLOT(downloadError(QNetworkReply::NetworkError)));
+    connect(rep, QOverload<QNetworkReply::NetworkError>::of(&QNetworkReply::error), this, &ImgurUpload::downloadError);
 #endif
+    connect(rep, &QNetworkReply::sslErrors, this, &ImgurUpload::sslErrors);
 }
+
 void ImgurUpload::downloadError(QNetworkReply::NetworkError error)
 {
     qCritical() << "ImgurUpload failed with error" << m_reply->errorString() << "Server reply:\n" << m_reply->readAll();
@@ -108,6 +110,7 @@ void ImgurUpload::downloadError(QNetworkReply::NetworkError error)
     m_reply.reset();
     emitFailed();
 }
+
 void ImgurUpload::downloadFinished()
 {
     if(finished)
@@ -144,6 +147,7 @@ void ImgurUpload::downloadFinished()
     emit succeeded();
     return;
 }
+
 void ImgurUpload::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
 {
     setProgress(bytesReceived, bytesTotal);
diff --git a/launcher/settings/SettingsObject.cpp b/launcher/settings/SettingsObject.cpp
index 8a0bc045..634acd34 100644
--- a/launcher/settings/SettingsObject.cpp
+++ b/launcher/settings/SettingsObject.cpp
@@ -132,11 +132,10 @@ bool SettingsObject::reload()
 
 void SettingsObject::connectSignals(const Setting &setting)
 {
-    connect(&setting, SIGNAL(SettingChanged(const Setting &, QVariant)),
-            SLOT(changeSetting(const Setting &, QVariant)));
-    connect(&setting, SIGNAL(SettingChanged(const Setting &, QVariant)),
+    connect(&setting, &Setting::SettingChanged, this, &SettingsObject::changeSetting);
+    connect(&setting, SIGNAL(SettingChanged(const Setting &, QVariant)), this,
             SIGNAL(SettingChanged(const Setting &, QVariant)));
 
-    connect(&setting, SIGNAL(settingReset(Setting)), SLOT(resetSetting(const Setting &)));
-    connect(&setting, SIGNAL(settingReset(Setting)), SIGNAL(settingReset(const Setting &)));
+    connect(&setting, &Setting::settingReset, this, &SettingsObject::resetSetting);
+    connect(&setting, SIGNAL(settingReset(Setting)), this, SIGNAL(settingReset(const Setting &)));
 }
diff --git a/launcher/tools/JProfiler.cpp b/launcher/tools/JProfiler.cpp
index 1dc0d109..15c0cab6 100644
--- a/launcher/tools/JProfiler.cpp
+++ b/launcher/tools/JProfiler.cpp
@@ -68,8 +68,8 @@ void JProfiler::beginProfilingImpl(shared_qobject_ptr<LaunchTask> process)
     profiler->setArguments(profilerArgs);
     profiler->setProgram(profilerProgram);
 
-    connect(profiler, SIGNAL(started()), SLOT(profilerStarted()));
-    connect(profiler, SIGNAL(finished(int, QProcess::ExitStatus)), SLOT(profilerFinished(int,QProcess::ExitStatus)));
+    connect(profiler, &QProcess::started, this, &JProfiler::profilerStarted);
+    connect(profiler, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), this, &JProfiler::profilerFinished);
 
     m_profilerProcess = profiler;
     profiler->start();
diff --git a/launcher/tools/JVisualVM.cpp b/launcher/tools/JVisualVM.cpp
index b1acc3c0..28ffb9cd 100644
--- a/launcher/tools/JVisualVM.cpp
+++ b/launcher/tools/JVisualVM.cpp
@@ -57,8 +57,8 @@ void JVisualVM::beginProfilingImpl(shared_qobject_ptr<LaunchTask> process)
     profiler->setArguments(profilerArgs);
     profiler->setProgram(programPath);
 
-    connect(profiler, SIGNAL(started()), SLOT(profilerStarted()));
-    connect(profiler, SIGNAL(finished(int, QProcess::ExitStatus)), SLOT(profilerFinished(int,QProcess::ExitStatus)));
+    connect(profiler, &QProcess::started, this, &JVisualVM::profilerStarted);
+    connect(profiler, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), this,  &JVisualVM::profilerFinished);
 
     profiler->start();
     m_profilerProcess = profiler;
diff --git a/launcher/ui/pages/instance/VersionPage.cpp b/launcher/ui/pages/instance/VersionPage.cpp
index 7fff3b93..fffb96f2 100644
--- a/launcher/ui/pages/instance/VersionPage.cpp
+++ b/launcher/ui/pages/instance/VersionPage.cpp
@@ -501,7 +501,7 @@ void VersionPage::on_actionDownload_All_triggered()
         return;
     }
     ProgressDialog tDialog(this);
-    connect(updateTask.get(), SIGNAL(failed(QString)), SLOT(onGameUpdateError(QString)));
+    connect(updateTask.get(), &Task::failed, this, &VersionPage::onGameUpdateError);
     // FIXME: unused return value
     tDialog.execWithTask(updateTask.get());
     updateButtons();