diff --git a/src/main/modules/ipc/main.ts b/src/main/modules/ipc/main.ts
index 9c3ab070c..c61e5f667 100644
--- a/src/main/modules/ipc/main.ts
+++ b/src/main/modules/ipc/main.ts
@@ -89,12 +89,15 @@ class MainProcessBridge implements MainIpcModule {
               data += chunk.toString()
             })
             res.on('end', () => {
+              // Extract runtime version from response header
+              const runtimeVersion = res.headers['x-openplc-runtime-version'] as string | undefined
+
               if (res.statusCode === 404) {
-                resolve({ hasUsers: false })
+                resolve({ hasUsers: false, runtimeVersion })
               } else if (res.statusCode === 200) {
-                resolve({ hasUsers: true })
+                resolve({ hasUsers: true, runtimeVersion })
               } else {
-                resolve({ hasUsers: false, error: data || `Unexpected status: ${res.statusCode}` })
+                resolve({ hasUsers: false, error: data || `Unexpected status: ${res.statusCode}`, runtimeVersion })
               }
             })
           },
diff --git a/src/main/modules/ipc/renderer.ts b/src/main/modules/ipc/renderer.ts
index b55b58744..dd526aa24 100644
--- a/src/main/modules/ipc/renderer.ts
+++ b/src/main/modules/ipc/renderer.ts
@@ -292,7 +292,7 @@ const rendererProcessBridge = {
   debuggerDisconnect: (): Promise<{ success: boolean }> => ipcRenderer.invoke('debugger:disconnect'),
 
   // ===================== RUNTIME API METHODS =====================
-  runtimeGetUsersInfo: (ipAddress: string): Promise<{ hasUsers: boolean; error?: string }> =>
+  runtimeGetUsersInfo: (ipAddress: string): Promise<{ hasUsers: boolean; runtimeVersion?: string; error?: string }> =>
     ipcRenderer.invoke('runtime:get-users-info', ipAddress),
   runtimeCreateUser: (
     ipAddress: string,
diff --git a/src/renderer/components/_features/[workspace]/editor/device/configuration/board.tsx b/src/renderer/components/_features/[workspace]/editor/device/configuration/board.tsx
index c4182e16a..36eff9182 100644
--- a/src/renderer/components/_features/[workspace]/editor/device/configuration/board.tsx
+++ b/src/renderer/components/_features/[workspace]/editor/device/configuration/board.tsx
@@ -7,7 +7,7 @@ import { Modal, ModalContent, ModalFooter, ModalHeader, ModalTitle } from '@root
 import { DeviceEditorSlot } from '@root/renderer/components/_templates/[editors]'
 import { useOpenPLCStore } from '@root/renderer/store'
 import type { DeviceActions, RuntimeConnection, TimingStats } from '@root/renderer/store/slices/device/types'
-import { cn, isArduinoTarget, isOpenPLCRuntimeTarget } from '@root/utils'
+import { cn, isArduinoTarget, isOpenPLCRuntimeTarget, validateRuntimeVersion } from '@root/utils'
 import { memo, useCallback, useEffect, useMemo, useRef, useState } from 'react'
 
 import { PinMappingTable } from './components/pin-mapping-table'
@@ -201,15 +201,61 @@ const Board = memo(function () {
         return
       }
 
-      if (result.hasUsers) {
-        openModal('runtime-login', null)
-      } else {
-        openModal('runtime-create-user', null)
+      // Validate runtime version matches the selected board target
+      const versionValidation = validateRuntimeVersion(deviceBoard, result.runtimeVersion)
+
+      // Helper to proceed with connection after validation
+      const proceedWithConnection = () => {
+        if (result.hasUsers) {
+          openModal('runtime-login', null)
+        } else {
+          openModal('runtime-create-user', null)
+        }
+      }
+
+      if (versionValidation.status === 'mismatch') {
+        // Hard error for version mismatch - cannot proceed
+        setRuntimeConnectionStatus('error')
+        openModal('debugger-message', {
+          type: 'error',
+          title: 'Runtime Version Mismatch',
+          message: versionValidation.message || 'Unknown version mismatch error',
+          buttons: ['OK'],
+          onResponse: () => {
+            // No action needed, just close the modal
+          },
+        })
+        return
       }
+
+      if (versionValidation.status === 'missing') {
+        // Warning for older runtimes - allow user to continue anyway
+        // Note: buttons ordered as ['Continue Anyway', 'Cancel'] so Cancel (index 1) is the default
+        // when closing the modal (DebuggerMessageModal calls onResponse with last button index on close)
+        openModal('debugger-message', {
+          type: 'warning',
+          title: 'Older Runtime Detected',
+          message: versionValidation.message || 'Could not detect runtime version.',
+          buttons: ['Continue Anyway', 'Cancel'],
+          onResponse: (buttonIndex: number) => {
+            if (buttonIndex === 0) {
+              // User clicked "Continue Anyway" - proceed with connection
+              proceedWithConnection()
+            } else {
+              // User clicked "Cancel" or closed the modal - stay disconnected
+              setRuntimeConnectionStatus('disconnected')
+            }
+          },
+        })
+        return
+      }
+
+      // Version is OK - proceed normally
+      proceedWithConnection()
     } catch (_error) {
       setRuntimeConnectionStatus('error')
     }
-  }, [runtimeIpAddress, connectionStatus, setRuntimeConnectionStatus, setRuntimeJwtToken, openModal])
+  }, [runtimeIpAddress, connectionStatus, setRuntimeConnectionStatus, setRuntimeJwtToken, openModal, deviceBoard])
 
   useEffect(() => {
     let statusInterval: NodeJS.Timeout | null = null
diff --git a/src/renderer/components/_organisms/modals/debugger-message-modal.tsx b/src/renderer/components/_organisms/modals/debugger-message-modal.tsx
index fb1d2f06a..2c12923d8 100644
--- a/src/renderer/components/_organisms/modals/debugger-message-modal.tsx
+++ b/src/renderer/components/_organisms/modals/debugger-message-modal.tsx
@@ -14,10 +14,14 @@ const DebuggerMessageModal = () => {
   } | null
 
   const handleButtonClick = (index: number) => {
-    if (modalData?.onResponse) {
-      modalData.onResponse(index)
-    }
+    // Capture callback before closing (closeModal clears data)
+    const onResponse = modalData?.onResponse
+    // Close modal first, then call callback to avoid race condition
+    // when callback opens another modal
     modalActions.closeModal()
+    if (onResponse) {
+      onResponse(index)
+    }
   }
 
   if (!modalData) return null
@@ -41,10 +45,15 @@ const DebuggerMessageModal = () => {
       open={isOpen}
       onOpenChange={(open) => {
         if (!open) {
-          if (modalData?.onResponse) {
-            modalData.onResponse(modalData.buttons.length - 1)
-          }
+          // Capture callback and button count before closing (closeModal clears data)
+          const onResponse = modalData?.onResponse
+          const lastButtonIndex = modalData?.buttons?.length ? modalData.buttons.length - 1 : 0
+          // Close modal first, then call callback to avoid race condition
+          // when callback opens another modal
           modalActions.closeModal()
+          if (onResponse) {
+            onResponse(lastButtonIndex)
+          }
         }
         modalActions.onOpenChange('debugger-message', open)
       }}
diff --git a/src/utils/device.ts b/src/utils/device.ts
index 21262cd35..8388fcd73 100644
--- a/src/utils/device.ts
+++ b/src/utils/device.ts
@@ -26,3 +26,66 @@ export function isOpenPLCRuntimeTarget(boardInfo: AvailableBoardInfo | undefined
   }
   return boardInfo.compiler === 'openplc-compiler'
 }
+
+/**
+ * Extracts the expected runtime version from the board target name.
+ * This is used to validate that the connected runtime matches the selected target.
+ *
+ * @param boardTarget - The board target name (e.g., "OpenPLC Runtime v3", "OpenPLC Runtime v4")
+ * @returns The expected runtime version string (e.g., "v3", "v4") or undefined if not a runtime target
+ */
+export function getExpectedRuntimeVersion(boardTarget: string): string | undefined {
+  const match = boardTarget.match(/OpenPLC Runtime (v\d+)/i)
+  return match ? match[1].toLowerCase() : undefined
+}
+
+/**
+ * Result of runtime version validation.
+ * - 'ok': Version matches or not a runtime target
+ * - 'missing': Runtime didn't report version (older runtime without header)
+ * - 'mismatch': Version reported but doesn't match selected target
+ */
+export type RuntimeVersionValidationResult = {
+  status: 'ok' | 'missing' | 'mismatch'
+  message?: string
+}
+
+/**
+ * Validates that the detected runtime version matches the expected version based on the selected board target.
+ *
+ * @param boardTarget - The selected board target name
+ * @param detectedVersion - The runtime version detected from the API response header
+ * @returns An object with status ('ok', 'missing', or 'mismatch') and an optional message
+ */
+export function validateRuntimeVersion(
+  boardTarget: string,
+  detectedVersion: string | undefined,
+): RuntimeVersionValidationResult {
+  const expectedVersion = getExpectedRuntimeVersion(boardTarget)
+
+  // If not a runtime target, no validation needed
+  if (!expectedVersion) {
+    return { status: 'ok' }
+  }
+
+  // If no version detected from runtime, it might be an older runtime without the header
+  if (!detectedVersion) {
+    return {
+      status: 'missing',
+      message:
+        'The runtime you are connecting to is older than the version of the editor. You may experience connection issues. Please update your runtime to the latest version.',
+    }
+  }
+
+  // Normalize detected version for comparison (expectedVersion is already lowercase from getExpectedRuntimeVersion)
+  const normalizedDetected = detectedVersion.toLowerCase()
+
+  if (normalizedDetected !== expectedVersion) {
+    return {
+      status: 'mismatch',
+      message: `Runtime version mismatch: Selected "${boardTarget}" but connected to a ${normalizedDetected.toUpperCase()} runtime. Please update your device configuration to match the connected runtime.`,
+    }
+  }
+
+  return { status: 'ok' }
+}