diff --git a/locales/en/messages.json b/locales/en/messages.json
index df26e79a..4d27d9fc 100644
--- a/locales/en/messages.json
+++ b/locales/en/messages.json
@@ -2818,6 +2818,14 @@
     "firmwareFlasherHexCorrupted": {
         "message": "HEX file appears to be corrupted"
     },
+    "firmwareFlasherConfigCorrupted": {
+        "message": "Config file appears to be corrupted, ASCII accepted (chars 0-255)",
+        "description": "shown in the progress bar at the bottom, be brief"
+    },
+    "firmwareFlasherConfigCorruptedLogMessage": {
+        "message": "Config file appears to be corrupted, ASCII accepted (chars 0-255), characters outside of this range are allowed as comments",
+        "description": "shown in the log, more wordy"
+    },
     "firmwareFlasherRemoteFirmwareLoaded": {
         "message": "<span class=\"message-positive\">Remote Firmware loaded, ready for flashing</span>"
     },
diff --git a/src/js/tabs/firmware_flasher.js b/src/js/tabs/firmware_flasher.js
index 6927e8ad..4a0f2882 100644
--- a/src/js/tabs/firmware_flasher.js
+++ b/src/js/tabs/firmware_flasher.js
@@ -612,6 +612,28 @@ TABS.firmware_flasher.initialize = function (callback) {
                 self.flashingMessage(i18n.getMessage('firmwareFlasherFirmwareLocalLoaded', self.parsed_hex.bytes_total), self.FLASH_MESSAGE_TYPES.NEUTRAL);
             }
         }
+        function cleanUnifiedConfigFile(input) {
+            let output = [];
+            let inComment = false;
+            for (let i=0; i < input.length; i++) {
+                if (input.charAt(i) == "\n" || input.charAt(i) == "\r") {
+                    inComment = false;
+                }
+                if (input.charAt(i) == "#") {
+                    inComment = true;
+                }
+                if (!inComment && input.charCodeAt(i) > 255) {
+                    // Note: we're not showing this error in betaflight-configurator
+                    throw new Error('commands are limited to characters 0-255, comments have no limitation');
+                }
+                if (input.charCodeAt(i) > 255) {
+                    output.push('_');
+                } else {
+                    output.push(input.charAt(i));
+                }
+            }
+            return output.join('');
+        }
         // UI Hooks
         $('a.load_file').click(function () {
             self.enableFlashing(false);
@@ -666,10 +688,15 @@ TABS.firmware_flasher.initialize = function (callback) {
                                     });
                                 } else {
                                     clearBufferedFirmware();
-                                    self.unifiedTargetConfig = e.target.result;
-                                    self.unifiedTargetConfigName = file.name;
-                                    self.isConfigLocal = true;
-                                    flashingMessageLocal();
+                                    try {
+                                        self.unifiedTargetConfig = cleanUnifiedConfigFile(e.target.result);
+                                        self.unifiedTargetConfigName = file.name;
+                                        self.isConfigLocal = true;
+                                        flashingMessageLocal();
+                                    } catch(err) {
+                                        self.flashingMessage('firmwareFlasherConfigCorrupted', self.FLASH_MESSAGE_TYPES.INVALID);
+                                        GUI.log(i18n.getMessage('firmwareFlasherConfigCorruptedLogMessage'));
+                                    }
                                 }
                             }
                         };