diff --git a/packages/frontend/src/components/MkImageGallery.item.vue b/packages/frontend/src/components/MkImageGallery.item.vue
index 5295422d1c..b809b86b85 100644
--- a/packages/frontend/src/components/MkImageGallery.item.vue
+++ b/packages/frontend/src/components/MkImageGallery.item.vue
@@ -31,7 +31,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 			<img
 				v-if="!originalImageLoaded || !thumbnailImageLoaded"
 				:class="[$style.image, $style.thumbnail]"
-				:src="image.thumbnailUrl"
+				:src="image.thumbnailUrl ?? image.url"
 				:width="image.width"
 				:height="image.height"
 				:style="{ width: `${imageRenderingSize.width}px`, height: `${imageRenderingSize.height}px` }"
@@ -66,7 +66,6 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 <script lang="ts" setup>
 import { nextTick, onBeforeUnmount, onMounted, onUnmounted, ref, useTemplateRef, watch } from 'vue';
-import * as os from '@/os.js';
 import { i18n } from '@/i18n.js';
 import { makeDoubleTapDetector } from '@/utility/double-tap.js';
 import { calculateSourceTransform } from '@/components/MkImageGallery.utils.js';
@@ -76,12 +75,12 @@ import { isTouchUsing } from '@/utility/touch.js';
 export type Image = {
 	id: string;
 	url: string;
-	thumbnailUrl: string;
+	thumbnailUrl: string | null;
 	width: number;
 	height: number;
-	filename?: string;
-	comment?: string;
-	sourceElement?: HTMLElement;
+	filename?: string | null;
+	comment?: string | null;
+	sourceElement?: HTMLElement | null;
 };
 
 const props = withDefaults(defineProps<{
@@ -108,6 +107,7 @@ const enableTransition = ref(false);
 const infoShowing = ref(false);
 
 onMounted(() => {
+	if (rootEl.value == null) return;
 	rootEl.value.offsetHeight; // reflow
 	infoShowing.value = true;
 });
@@ -163,6 +163,8 @@ if (props.image.sourceElement != null && props.activated) {
 const isZooming = ref(false);
 
 function zoomInTo(x: number, y: number, factor = 1.1, withAnimation = false) {
+	if (mainEl.value == null) return;
+
 	const newScale = transform.value.scale * factor;
 	isZooming.value = true;
 
@@ -183,6 +185,8 @@ function zoomInTo(x: number, y: number, factor = 1.1, withAnimation = false) {
 }
 
 function resetToNeutral() {
+	if (rootEl.value == null) return;
+
 	isZooming.value = false;
 
 	enableTransition.value = true;
@@ -195,6 +199,8 @@ function resetToNeutral() {
 function closeThis() {
 	emit('close');
 
+	if (rootEl.value == null) return;
+
 	infoShowing.value = false;
 
 	const sourceTransform = getScaleAndTranslationForSourceElement();
@@ -254,6 +260,7 @@ const pointerEventCache = new Map<number, PointerEvent>();
 let pointerVec = { x: 0, y: 0 };
 
 function onPointerdown(ev: PointerEvent) {
+	if (mainEl.value == null) return;
 	pointerEventCache.set(ev.pointerId, ev);
 	mainEl.value.setPointerCapture(ev.pointerId);
 
@@ -344,6 +351,7 @@ function onPointermove(ev: PointerEvent) {
 }
 
 function onPointerup(ev: PointerEvent) {
+	if (mainEl.value == null) return;
 	pointerEventCache.delete(ev.pointerId);
 	mainEl.value.releasePointerCapture(ev.pointerId);
 	prevTwoTouchPointsDistance = 0;
@@ -453,7 +461,10 @@ onBeforeUnmount(() => {
 //#endregion
 
 watch(thumbnailImageLoaded, () => {
-	if (props.image.sourceElement != null && props.activated) {
+	if (rootEl.value == null) return;
+
+	const sourceElement = props.image.sourceElement;
+	if (sourceElement != null && props.activated) {
 		enableTransition.value = true;
 		rootEl.value.offsetHeight; // reflow
 		transform.value.x = 0;
@@ -461,7 +472,7 @@ watch(thumbnailImageLoaded, () => {
 		transform.value.scale = 1;
 
 		nextTick(() => {
-			props.image.sourceElement.style.visibility = 'hidden';
+			sourceElement.style.visibility = 'hidden';
 		});
 	}
 }, { once: true });
diff --git a/packages/frontend/src/components/MkImageGallery.vue b/packages/frontend/src/components/MkImageGallery.vue
index 319a4617a7..12f57a8159 100644
--- a/packages/frontend/src/components/MkImageGallery.vue
+++ b/packages/frontend/src/components/MkImageGallery.vue
@@ -71,7 +71,10 @@ watch(currentIndex, (newIndex) => {
 }, { immediate: true });
 watch(currentIndex, (newIndex) => {
 	for (let i = 0; i < props.images.length; i++) {
-		props.images[i].sourceElement.style.visibility = i === newIndex ? 'hidden' : '';
+		const image = props.images[i];
+		if (image.sourceElement != null) {
+			image.sourceElement.style.visibility = i === newIndex ? 'hidden' : '';
+		}
 	}
 }, { immediate: false });
 
diff --git a/packages/frontend/src/components/MkMediaList.vue b/packages/frontend/src/components/MkMediaList.vue
index 39178e40da..06ae1a0d48 100644
--- a/packages/frontend/src/components/MkMediaList.vue
+++ b/packages/frontend/src/components/MkMediaList.vue
@@ -96,6 +96,12 @@ const previewable = (file: Misskey.entities.DriveFile): boolean => {
 };
 
 async function openGallery(id: string) {
+	const getElementByMarker = (marker: string) => {
+		if (gallery.value == null) return null;
+		const found = gallery.value.querySelector(`[data-marker="${marker}"]`) as HTMLElement | null;
+		if (found == null) return null;
+		return markRaw(found);
+	};
 	const images = props.mediaList.filter(media => previewable(media)).map(media => ({
 		id: media.id,
 		url: media.url,
@@ -104,7 +110,7 @@ async function openGallery(id: string) {
 		height: media.properties.height ?? 0,
 		filename: media.name,
 		comment: media.comment,
-		sourceElement: markRaw(gallery.value?.querySelector(`[data-marker="${markerId}:${media.id}"]`)),
+		sourceElement: getElementByMarker(`${markerId}:${media.id}`),
 	}));
 	const { dispose } = await os.popupAsyncWithDialog(import('@/components/MkImageGallery.vue').then(x => x.default), {
 		defaultIndex: images.findIndex(image => image.id === id),