diff --git a/CHANGELOG.md b/CHANGELOG.md
index 84cf61f028..c492e43839 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,12 @@ ChangeLog
 
 This document describes breaking changes only.
 
+9.0.0
+-----
+
+Misskey v8.64.0 を使っている方は、9.0.0に際しては特にすべきことはありません。
+Misskey v8.64.0 に満たないバージョンをお使いの方は、一旦8.64.0にアップデートして(そして起動して)から9.0.0に再度アップデートしてください。
+
 8.0.0
 -----
 
diff --git a/package.json b/package.json
index 1c45fc7aff..17603790f0 100644
--- a/package.json
+++ b/package.json
@@ -1,8 +1,8 @@
 {
 	"name": "misskey",
 	"author": "syuilo <i@syuilo.com>",
-	"version": "8.64.0",
-	"clientVersion": "1.0.10046",
+	"version": "9.0.0",
+	"clientVersion": "1.0.10049",
 	"codename": "nighthike",
 	"main": "./built/index.js",
 	"private": true,
diff --git a/src/models/note.ts b/src/models/note.ts
index f67eeaaf6e..0efabc97d8 100644
--- a/src/models/note.ts
+++ b/src/models/note.ts
@@ -27,21 +27,6 @@ Note.createIndex({
 });
 export default Note;
 
-// 後方互換性のため
-Note.findOne({
-	fileIds: { $exists: true }
-}).then(n => {
-	if (n == null) {
-		Note.update({}, {
-			$rename: {
-				mediaIds: 'fileIds'
-			}
-		}, {
-			multi: true
-		});
-	}
-});
-
 export function isValidText(text: string): boolean {
 	return length(text.trim()) <= 1000 && text.trim() != '';
 }
diff --git a/src/models/stats.ts b/src/models/stats.ts
index c4c838caeb..492784555e 100644
--- a/src/models/stats.ts
+++ b/src/models/stats.ts
@@ -3,11 +3,6 @@ import db from '../db/mongodb';
 
 const Stats = db.get<IStats>('stats');
 
-// 後方互換性のため
-Stats.dropIndex({ date: -1 } as any).catch((e: mongo.MongoError) => {
-	if (e.code !== 27) throw e;
-});
-
 Stats.createIndex({ span: -1, date: -1 }, { unique: true });
 export default Stats;
 
diff --git a/src/models/user.ts b/src/models/user.ts
index bacae485a8..8ff91d3f45 100644
--- a/src/models/user.ts
+++ b/src/models/user.ts
@@ -35,28 +35,6 @@ User.createIndex('uri', { sparse: true, unique: true });
 
 export default User;
 
-// 後方互換性のため
-User.findOne({
-	pinnedNoteId: { $exists: true }
-}).then(async x => {
-	if (x == null) return;
-
-	const users = await User.find({
-		pinnedNoteId: { $exists: true }
-	});
-
-	users.forEach(u => {
-		User.update({ _id: u._id }, {
-			$set: {
-				pinnedNoteIds: [(u as any).pinnedNoteId]
-			},
-			$unset: {
-				pinnedNoteId: ''
-			}
-		});
-	});
-});
-
 type IUserBase = {
 	_id: mongo.ObjectID;
 	createdAt: Date;