diff --git a/packages/backend/src/server/api/mastodon/MastodonConverters.ts b/packages/backend/src/server/api/mastodon/MastodonConverters.ts
index 0e8ce5a2a7..e5d732ed79 100644
--- a/packages/backend/src/server/api/mastodon/MastodonConverters.ts
+++ b/packages/backend/src/server/api/mastodon/MastodonConverters.ts
@@ -351,12 +351,21 @@ export class MastodonConverters {
 		};
 	}
 
-	public async convertNotification(notification: Entity.Notification, me: MiLocalUser | null): Promise<MastodonEntity.Notification> {
+	public async convertNotification(notification: Entity.Notification, me: MiLocalUser | null): Promise<MastodonEntity.Notification | null> {
+		const status = notification.status
+			? await this.convertStatus(notification.status, me).catch(() => null)
+			: null;
+
+		// We sometimes get notifications for inaccessible notes, these should be ignored.
+		if (!status) {
+			return null;
+		}
+
 		return {
 			account: await this.convertAccount(notification.account),
 			created_at: notification.created_at,
 			id: notification.id,
-			status: notification.status ? await this.convertStatus(notification.status, me) : undefined,
+			status,
 			type: convertNotificationType(notification.type as NotificationType),
 		};
 	}
diff --git a/packages/backend/src/server/api/mastodon/MastodonLogger.ts b/packages/backend/src/server/api/mastodon/MastodonLogger.ts
index 57cf876dff..81d3e8f03d 100644
--- a/packages/backend/src/server/api/mastodon/MastodonLogger.ts
+++ b/packages/backend/src/server/api/mastodon/MastodonLogger.ts
@@ -35,7 +35,7 @@ export class MastodonLogger {
 // TODO move elsewhere
 export interface MastodonError {
 	error: string;
-	error_description: string;
+	error_description?: string;
 }
 
 export function getErrorData(error: unknown): MastodonError {
diff --git a/packages/backend/src/server/api/mastodon/endpoints/notifications.ts b/packages/backend/src/server/api/mastodon/endpoints/notifications.ts
index c81b3ca236..c3108c8b3e 100644
--- a/packages/backend/src/server/api/mastodon/endpoints/notifications.ts
+++ b/packages/backend/src/server/api/mastodon/endpoints/notifications.ts
@@ -32,6 +32,9 @@ export class ApiNotificationsMastodon {
 			const notifications = await Promise.all(data.data.map(n => this.mastoConverters.convertNotification(n, me)));
 			const response: MastodonEntity.Notification[] = [];
 			for (const notification of notifications) {
+				// Notifications for inaccessible notes will be null and should be ignored
+				if (!notification) continue;
+
 				response.push(notification);
 				if (notification.type === 'reaction') {
 					response.push({
@@ -52,6 +55,13 @@ export class ApiNotificationsMastodon {
 			const data = await client.getNotification(_request.params.id);
 			const response = await this.mastoConverters.convertNotification(data.data, me);
 
+			// Notifications for inaccessible notes will be null and should be ignored
+			if (!response) {
+				return reply.code(404).send({
+					error: 'NOT_FOUND',
+				});
+			}
+
 			reply.send(response);
 		});