diff --git a/src/controller/controller.cpp b/src/controller/controller.cpp
index 4bbbd9f7..5894e103 100644
--- a/src/controller/controller.cpp
+++ b/src/controller/controller.cpp
@@ -101,15 +101,6 @@ void Controller::run()
 
         startCommandExecution();
 
-    } catch (const std::invalid_argument& exc) {
-        if (isInStdinMode) {
-            // Pass invalid argument message to the caller just in case it may be interested
-            // The result will be {"invalid-argument" : message}
-            // Command parameter is only used if exception will be raised during json creation
-            writeResponseToStdOut(isInStdinMode, {{QStringLiteral("invalid-argument"), exc.what()}},
-                                  "invalid-argument");
-        }
-        onCriticalFailure(exc.what());
     } catch (const std::exception& error) {
         onCriticalFailure(error.what());
     }
diff --git a/src/ui/webeiddialog.cpp b/src/ui/webeiddialog.cpp
index 261319b5..76f7ab75 100644
--- a/src/ui/webeiddialog.cpp
+++ b/src/ui/webeiddialog.cpp
@@ -20,8 +20,6 @@
  * SOFTWARE.
  */
 
-#include "utils/erasedata.hpp"
-
 #include "webeiddialog.hpp"
 #include "application.hpp"
 #include "punycode.hpp"
@@ -292,7 +290,8 @@ QString WebEidDialog::getPin()
     // QString uses QAtomicPointer internally and is thread-safe.
     // There should be only single reference and this is transferred to the caller for safety
     QString ret = pin;
-    eraseData(pin);
+    // Cannot use eraseData because we have to force Qt copy-on-write
+    pin.fill('\0');
     pin.clear();
     return ret;
 }
@@ -464,7 +463,6 @@ void WebEidDialog::onVerifyPinFailed(const VerifyPinFailed::Status status, const
         break;
     case Status::PIN_BLOCKED:
         displayPinBlockedError();
-        resizeHeight();
         return;
     case Status::INVALID_PIN_LENGTH:
         message = [] { return tr("Invalid PIN length"); };
@@ -481,7 +479,7 @@ void WebEidDialog::onVerifyPinFailed(const VerifyPinFailed::Status status, const
     case Status::UNKNOWN_ERROR:
         message = [] { return tr("Technical error"); };
         displayFatalError(message);
-        break;
+        return;
     }
 
     ui->pinErrorLabel->setVisible(bool(message));
@@ -681,17 +679,7 @@ void WebEidDialog::setupOK(Func func, const char* text, bool enabled)
 
 void WebEidDialog::displayPinBlockedError()
 {
-    ui->pinTitleLabel->hide();
-    ui->pinInput->hide();
-    ui->pinTimeoutTimer->stop();
-    ui->pinTimeRemaining->hide();
-    ui->pinEntryTimeoutProgressBar->hide();
-    setTrText(ui->pinErrorLabel, QT_TR_NOOP("PIN is locked. Unblock and try again."));
-    ui->pinErrorLabel->show();
-    ui->okButton->hide();
-    ui->cancelButton->setEnabled(true);
-    ui->cancelButton->show();
-    ui->helpButton->show();
+    displayFatalError([] { return tr("PIN is locked. Unblock and try again."); });
 }
 
 void WebEidDialog::displayFatalError(std::function<QString()> message)
@@ -706,6 +694,8 @@ void WebEidDialog::displayFatalError(std::function<QString()> message)
     ui->okButton->hide();
     ui->cancelButton->setEnabled(true);
     ui->cancelButton->show();
+    ui->helpButton->show();
+    resizeHeight();
 }
 
 void WebEidDialog::showPinInputWarning(bool show)