diff --git a/packages/backend/src/server/api/endpoints/notes/hybrid-timeline.ts b/packages/backend/src/server/api/endpoints/notes/hybrid-timeline.ts
index 917792a7ff..2b25bec1c5 100644
--- a/packages/backend/src/server/api/endpoints/notes/hybrid-timeline.ts
+++ b/packages/backend/src/server/api/endpoints/notes/hybrid-timeline.ts
@@ -201,7 +201,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				}
 
 				const config = loadConfig();
-				const defaultTag: string | null = config.tagging.defaultTag;
+				const defaultTag: string | null = config.tagging?.defaultTag;
 				if (defaultTag == null) {
 					qb.orWhere('(note.visibility = \'public\') AND (note.userHost IS NULL)');
 				} else {
diff --git a/packages/backend/src/server/api/endpoints/notes/local-timeline.ts b/packages/backend/src/server/api/endpoints/notes/local-timeline.ts
index 24f8a303e8..642eb57ed9 100644
--- a/packages/backend/src/server/api/endpoints/notes/local-timeline.ts
+++ b/packages/backend/src/server/api/endpoints/notes/local-timeline.ts
@@ -152,7 +152,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		withReplies: boolean,
 	}, me: MiLocalUser | null) {
 		const config = loadConfig();
-		const defaultTag: string | null = config.tagging.defaultTag;
+		const defaultTag: string | null = config.tagging?.defaultTag;
 		const query = this.queryService.makePaginationQuery(this.notesRepository.createQueryBuilder('note'),
 			ps.sinceId, ps.untilId)
 				.andWhere(new Brackets(qb => {
diff --git a/packages/backend/src/server/api/stream/channels/hybrid-timeline.ts b/packages/backend/src/server/api/stream/channels/hybrid-timeline.ts
index dab99ba400..38196a9c68 100644
--- a/packages/backend/src/server/api/stream/channels/hybrid-timeline.ts
+++ b/packages/backend/src/server/api/stream/channels/hybrid-timeline.ts
@@ -47,7 +47,7 @@ class HybridTimelineChannel extends Channel {
 		this.withReplies = params.withReplies ?? false;
 		this.withFiles = params.withFiles ?? false;
 		const config = loadConfig();
-		this.defaultTag = config.tagging.defaultTag;
+		this.defaultTag = config.tagging?.defaultTag;
 
 		// Subscribe events
 		this.subscriber.on('notesStream', this.onNote);