diff --git a/src/js/serial_backend.js b/src/js/serial_backend.js
index 2dcbc52c..deff37ba 100644
--- a/src/js/serial_backend.js
+++ b/src/js/serial_backend.js
@@ -239,6 +239,26 @@ function setConnectionTimeout() {
     }, 10000);
 }
 
+function abortConnection() {
+    GUI.timeout_remove('connecting'); // kill connecting timer
+
+    GUI.connected_to = false;
+    GUI.connecting_to = false;
+
+    tracking.sendEvent(tracking.EVENT_CATEGORIES.FLIGHT_CONTROLLER, 'SerialPortFailed');
+
+    gui_log(i18n.getMessage('serialPortOpenFail'));
+
+    $('div#connectbutton div.connect_state').text(i18n.getMessage('connect'));
+    $('div#connectbutton a.connect').removeClass('active');
+
+    // unlock port select & baud
+    $('div#port-picker #port, div#port-picker #baud, div#port-picker #delay').prop('disabled', false);
+
+    // reset data
+    clicks = false;
+}
+
 function onOpen(openInfo) {
     if (openInfo) {
         CONFIGURATOR.virtualMode = false;
@@ -275,12 +295,16 @@ function onOpen(openInfo) {
         console.log(`Requesting configuration data`);
 
         MSP.send_message(MSPCodes.MSP_API_VERSION, false, false, function () {
+            gui_log(i18n.getMessage('apiVersionReceived', FC.CONFIG.apiVersion));
+
+            if (FC.CONFIG.apiVersion.includes('null')) {
+                abortConnection();
+                return;
+            }
+
             tracking.setFlightControllerData(tracking.DATA.API_VERSION, FC.CONFIG.apiVersion);
 
-            gui_log(i18n.getMessage('apiVersionReceived', [FC.CONFIG.apiVersion]));
-
             if (semver.gte(FC.CONFIG.apiVersion, CONFIGURATOR.API_VERSION_ACCEPTED)) {
-
                 MSP.send_message(MSPCodes.MSP_FC_VARIANT, false, false, function () {
                     tracking.setFlightControllerData(tracking.DATA.FIRMWARE_TYPE, FC.CONFIG.flightControllerIdentifier);
                     if (FC.CONFIG.flightControllerIdentifier === 'BTFL') {
@@ -329,12 +353,7 @@ function onOpen(openInfo) {
             }
         });
     } else {
-        tracking.sendEvent(tracking.EVENT_CATEGORIES.FLIGHT_CONTROLLER, 'SerialPortFailed');
-
-        console.log('Failed to open serial port');
-        gui_log(i18n.getMessage('serialPortOpenFail'));
-
-        abortConnect();
+        abortConnection();
     }
 }
 
@@ -355,17 +374,6 @@ function onOpenVirtual() {
     updateTabList(FC.FEATURE_CONFIG.features);
 }
 
-function abortConnect() {
-    $('div#connectbutton div.connect_state').text(i18n.getMessage('connect'));
-    $('div#connectbutton a.connect').removeClass('active');
-
-    // unlock port select & baud
-    $('div#port-picker #port, div#port-picker #baud, div#port-picker #delay').prop('disabled', false);
-
-    // reset data
-    clicks = false;
-}
-
 function processCustomDefaults() {
     if (bit_check(FC.CONFIG.targetCapabilities, FC.TARGET_CAPABILITIES_FLAGS.SUPPORTS_CUSTOM_DEFAULTS) && bit_check(FC.CONFIG.targetCapabilities, FC.TARGET_CAPABILITIES_FLAGS.HAS_CUSTOM_DEFAULTS) && FC.CONFIG.configurationState === FC.CONFIGURATION_STATES.DEFAULTS_BARE) {
         const dialog = $('#dialogResetToCustomDefaults')[0];
diff --git a/src/js/tabs/firmware_flasher.js b/src/js/tabs/firmware_flasher.js
index aa71656e..46200376 100644
--- a/src/js/tabs/firmware_flasher.js
+++ b/src/js/tabs/firmware_flasher.js
@@ -539,7 +539,11 @@ firmware_flasher.initialize = function (callback) {
                     MSP.clearListeners();
                 }
 
-                function onClose() {
+                function onClose(success) {
+                    if (!success) {
+                        gui_log(i18n.getMessage('firmwareFlasherBoardVerificationFailed'));
+                    }
+
                     serial.disconnect(onFinishClose);
                     MSP.disconnect_cleanup();
                 }
@@ -564,11 +568,10 @@ firmware_flasher.initialize = function (callback) {
 
                         gui_log(i18n.getMessage(targetAvailable ? 'firmwareFlasherBoardVerificationSuccess' : 'firmwareFlasherBoardVerficationTargetNotAvailable',
                             { boardName: board }));
+                        onClose(true);
                     } else {
-                        gui_log(i18n.getMessage('firmwareFlasherBoardVerificationFail'));
+                        onClose(false);
                     }
-
-                    onClose();
                 }
 
                 function getBoardInfo() {
@@ -598,12 +601,11 @@ firmware_flasher.initialize = function (callback) {
                 function detectBoard() {
                     console.log(`Requesting board information`);
                     MSP.send_message(MSPCodes.MSP_API_VERSION, false, false, () => {
-                        if (!FC.CONFIG.apiVersion || FC.CONFIG.apiVersion === 'null.null.0') {
-                            FC.CONFIG.apiVersion = '0.0.0';
-                        }
-
-                        if (semver.lt(FC.CONFIG.apiVersion, API_VERSION_1_39)) {
-                            onClose(); // not supported
+                        if (!FC.CONFIG.apiVersion || FC.CONFIG.apiVersion.includes('null')) {
+                            gui_log(i18n.getMessage('apiVersionReceived', FC.CONFIG.apiVersion));
+                            onClose(false); // not supported
+                        } else if (semver.lt(FC.CONFIG.apiVersion, API_VERSION_1_39)) {
+                            onClose(false); // not supported
                         } else {
                             MSP.send_message(MSPCodes.MSP_UID, false, false, getBuildInfo);
                         }