diff --git a/apps/theming/lib/ImageManager.php b/apps/theming/lib/ImageManager.php
index 309bf192bc3..8ba558d7947 100644
--- a/apps/theming/lib/ImageManager.php
+++ b/apps/theming/lib/ImageManager.php
@@ -202,8 +202,6 @@ class ImageManager {
 	}
 
 	public function updateImage(string $key, string $tmpFile): string {
-		$this->delete($key);
-
 		try {
 			$folder = $this->getRootFolder()->getFolder('images');
 		} catch (NotFoundException $e) {
@@ -217,6 +215,8 @@ class ImageManager {
 			throw new \Exception('Unsupported image type: ' . $detectedMimeType);
 		}
 
+		$this->delete($key);
+
 		if ($key === 'background') {
 			if ($this->shouldOptimizeBackgroundImage($detectedMimeType, filesize($tmpFile))) {
 				try {
diff --git a/apps/theming/src/components/admin/FileInputField.vue b/apps/theming/src/components/admin/FileInputField.vue
index 581b69570a4..1af133d6991 100644
--- a/apps/theming/src/components/admin/FileInputField.vue
+++ b/apps/theming/src/components/admin/FileInputField.vue
@@ -76,8 +76,17 @@ async function onChange() {
 		})
 		mime.value = file.type
 		emit('updated')
+	} catch (error: any) {
+		if (error?.response?.status === 422) {
+			const serverMessage = error.response.data?.data?.message
+			showError(serverMessage || t('theming', 'Failed to upload image'))
+		} else {
+			showError(t('theming', 'Failed to upload image'))
+		}
 	} finally {
 		isSaving.value = false
+		// Reset input to allow re-selecting the same file and show validation errors on every attempt
+		inputElement.value!.value = ''
 	}
 }