diff --git a/packages/backend/src/core/activitypub/ApInboxService.ts b/packages/backend/src/core/activitypub/ApInboxService.ts
index 2f285a17cb..57b30788bd 100644
--- a/packages/backend/src/core/activitypub/ApInboxService.ts
+++ b/packages/backend/src/core/activitypub/ApInboxService.ts
@@ -388,7 +388,7 @@ export class ApInboxService {
 	}
 
 	@bindThis
-	private async create(actor: MiRemoteUser, activity: ICreate, resolver?: Resolver): Promise<string | void> {
+	private async create(actor: MiRemoteUser, activity: ICreate | IUpdate, resolver?: Resolver): Promise<string | void> {
 		const uri = getApId(activity);
 
 		this.logger.info(`Create: ${uri}`);
@@ -423,14 +423,14 @@ export class ApInboxService {
 		});
 
 		if (isPost(object)) {
-			await this.createNote(resolver, actor, object, false, activity);
+			await this.createNote(resolver, actor, object, false);
 		} else {
 			return `Unknown type: ${getApType(object)}`;
 		}
 	}
 
 	@bindThis
-	private async createNote(resolver: Resolver, actor: MiRemoteUser, note: IObject, silent = false, activity?: ICreate): Promise<string> {
+	private async createNote(resolver: Resolver, actor: MiRemoteUser, note: IObject, silent = false): Promise<string> {
 		const uri = getApId(note);
 
 		if (typeof note === 'object') {
@@ -789,7 +789,7 @@ export class ApInboxService {
 	}
 
 	@bindThis
-	private async update(actor: MiRemoteUser, activity: IUpdate, resolver?: Resolver): Promise<string> {
+	private async update(actor: MiRemoteUser, activity: IUpdate, resolver?: Resolver): Promise<string | void> {
 		if (actor.uri !== activity.actor) {
 			return 'skip: invalid actor';
 		}
@@ -808,9 +808,19 @@ export class ApInboxService {
 			await this.apPersonService.updatePerson(actor.uri, resolver, object);
 			return 'ok: Person updated';
 		} else if (getApType(object) === 'Question') {
+			// If we get an Update(Question) for a note that doesn't exist, then create it instead
+			if (!await this.apNoteService.hasNote(object)) {
+				return await this.create(actor, activity, resolver);
+			}
+
 			await this.apQuestionService.updateQuestion(object, actor, resolver).catch(err => console.error(err));
 			return 'ok: Question updated';
 		} else if (isPost(object)) {
+			// If we get an Update(Note) for a note that doesn't exist, then create it instead
+			if (!await this.apNoteService.hasNote(object)) {
+				return await this.create(actor, activity, resolver);
+			}
+
 			await this.apNoteService.updateNote(object, actor, resolver).catch(err => console.error(err));
 			return 'ok: Note updated';
 		} else {
diff --git a/packages/backend/src/core/activitypub/models/ApNoteService.ts b/packages/backend/src/core/activitypub/models/ApNoteService.ts
index a0ddc2075b..a6d2ee1887 100644
--- a/packages/backend/src/core/activitypub/models/ApNoteService.ts
+++ b/packages/backend/src/core/activitypub/models/ApNoteService.ts
@@ -142,6 +142,15 @@ export class ApNoteService {
 		return await this.apDbResolverService.getNoteFromApId(object);
 	}
 
+	/**
+	 * Returns true if the provided object / ID exists in the local database.
+	 */
+	@bindThis
+	public async hasNote(object: string | IObject | [string | IObject]): Promise<boolean> {
+		const uri = getApId(object);
+		return await this.notesRepository.existsBy({ uri });
+	}
+
 	/**
 	 * Noteを作成します。
 	 */