fix(windows): skip DPI awareness API call when already set via manifest

v3/UNRELEASED_CHANGELOG.md

@@ -23,6 +23,7 @@ After processing, the content will be moved to the main changelog and this file
 
 ## Fixed
 <!-- Bug fixes -->
+- Fix SetProcessDpiAwarenessContext "Access is denied" error when DPI awareness is already set via application manifest (#4803)
 
 ## Deprecated
 <!-- Soon-to-be removed features -->

v3/pkg/application/application_windows.go

@@ -358,6 +358,18 @@ func setupDPIAwareness() error {
 	// https://learn.microsoft.com/en-us/windows/win32/hidpi/setting-the-default-dpi-awareness-for-a-process
 	// https://learn.microsoft.com/en-us/windows/win32/hidpi/high-dpi-desktop-application-development-on-windows
 
+	// Check if DPI awareness has already been set (e.g., via application manifest).
+	// Windows only allows setting DPI awareness once per process - either via manifest
+	// or API, not both. If already set, skip the API call to avoid "Access is denied" errors.
+	// See: https://github.com/wailsapp/wails/issues/4803
+	if w32.HasGetProcessDpiAwarenessFunc() {
+		awareness, err := w32.GetProcessDpiAwareness()
+		if err == nil && awareness != w32.PROCESS_DPI_UNAWARE {
+			// DPI awareness already set (likely via manifest), skip API call
+			return nil
+		}
+	}
+
 	if w32.HasSetProcessDpiAwarenessContextFunc() {
 		// This is most recent version with the best results
 		// supported beginning with Windows 10, version 1703

v3/pkg/w32/shcore.go

@@ -12,9 +12,26 @@ var (
 	modshcore = syscall.NewLazyDLL("shcore.dll")
 
 	procGetDpiForMonitor       = modshcore.NewProc("GetDpiForMonitor")
+	procGetProcessDpiAwareness = modshcore.NewProc("GetProcessDpiAwareness")
 	procSetProcessDpiAwareness = modshcore.NewProc("SetProcessDpiAwareness")
 )
 
+func HasGetProcessDpiAwarenessFunc() bool {
+	err := procGetProcessDpiAwareness.Find()
+	return err == nil
+}
+
+// GetProcessDpiAwareness retrieves the DPI awareness of the current process.
+// Returns one of: PROCESS_DPI_UNAWARE, PROCESS_SYSTEM_DPI_AWARE, or PROCESS_PER_MONITOR_DPI_AWARE.
+func GetProcessDpiAwareness() (uint, error) {
+	var awareness uint
+	status, _, err := procGetProcessDpiAwareness.Call(0, uintptr(unsafe.Pointer(&awareness)))
+	if status != S_OK {
+		return 0, fmt.Errorf("GetProcessDpiAwareness failed: %v", err)
+	}
+	return awareness, nil
+}
+
 func HasSetProcessDpiAwarenessFunc() bool {
 	err := procSetProcessDpiAwareness.Find()
 	return err == nil