diff --git a/keyboard_layout.cpp b/keyboard_layout.cpp
--- a/keyboard_layout.cpp
+++ b/keyboard_layout.cpp
@@ -269,13 +269,11 @@
             p->setProcessEnvironment(kwinApp()->processStartupEnvironment());
             p->setProgram(QStringLiteral("kcmshell5"));
             connect(p, static_cast<void (QProcess::*)(int, QProcess::ExitStatus)>(&QProcess::finished), p, &QProcess::deleteLater);
-            connect(p, static_cast<void (QProcess::*)(QProcess::ProcessError)>(&QProcess::error), this,
-                [] (QProcess::ProcessError e) {
-                    if (e == QProcess::FailedToStart) {
-                        qCDebug(KWIN_CORE) << "Failed to start kcmshell5";
-                    }
+            connect(p, &QProcess::errorOccurred, this, [](QProcess::ProcessError e) {
+                if (e == QProcess::FailedToStart) {
+                    qCDebug(KWIN_CORE) << "Failed to start kcmshell5";
                 }
-            );
+            });
             p->start();
         }
     );
diff --git a/rules.cpp b/rules.cpp
--- a/rules.cpp
+++ b/rules.cpp
@@ -1051,13 +1051,11 @@
     p->setProgram(buildDirBinary.exists() ? buildDirBinary.absoluteFilePath() : QStringLiteral(KWIN_RULES_DIALOG_BIN));
     p->setProcessChannelMode(QProcess::MergedChannels);
     connect(p, static_cast<void (QProcess::*)(int, QProcess::ExitStatus)>(&QProcess::finished), p, &QProcess::deleteLater);
-    connect(p, static_cast<void (QProcess::*)(QProcess::ProcessError)>(&QProcess::error), this,
-        [p] (QProcess::ProcessError e) {
-            if (e == QProcess::FailedToStart) {
-                qCDebug(KWIN_CORE) << "Failed to start" << p->program();
-            }
+    connect(p, &QProcess::errorOccurred, this, [p](QProcess::ProcessError e) {
+        if (e == QProcess::FailedToStart) {
+            qCDebug(KWIN_CORE) << "Failed to start" << p->program();
         }
-    );
+    });
     p->start();
 }
 
diff --git a/useractions.cpp b/useractions.cpp
--- a/useractions.cpp
+++ b/useractions.cpp
@@ -327,13 +327,11 @@
                 p->setProcessEnvironment(kwinApp()->processStartupEnvironment());
                 p->setProgram(QStringLiteral("kcmshell5"));
                 connect(p, static_cast<void (QProcess::*)(int, QProcess::ExitStatus)>(&QProcess::finished), p, &QProcess::deleteLater);
-                connect(p, static_cast<void (QProcess::*)(QProcess::ProcessError)>(&QProcess::error), this,
-                    [p] (QProcess::ProcessError e) {
-                        if (e == QProcess::FailedToStart) {
-                            qCDebug(KWIN_CORE) << "Failed to start kcmshell5";
-                        }
+                connect(p, &QProcess::errorOccurred, this, [p](QProcess::ProcessError e) {
+                    if (e == QProcess::FailedToStart) {
+                        qCDebug(KWIN_CORE) << "Failed to start kcmshell5";
                     }
-                );
+                });
                 p->start();
             }
         );
diff --git a/xwl/xwayland.cpp b/xwl/xwayland.cpp
--- a/xwl/xwayland.cpp
+++ b/xwl/xwayland.cpp
@@ -155,7 +155,7 @@
                            QStringLiteral("-rootless"),
                            QStringLiteral("-wm"),
                            QString::number(fd)});
-    m_xwaylandFailConnection = connect(m_xwaylandProcess, static_cast<void (QProcess::*)(QProcess::ProcessError)>(&QProcess::error), this,
+    m_xwaylandFailConnection = connect(m_xwaylandProcess, &QProcess::errorOccurred, this,
         [this] (QProcess::ProcessError error) {
             if (error == QProcess::FailedToStart) {
                 std::cerr << "FATAL ERROR: failed to start Xwayland" << std::endl;