diff --git a/packages/backend/src/models/Meta.ts b/packages/backend/src/models/Meta.ts
index 63e2331915..9f1da8b0fd 100644
--- a/packages/backend/src/models/Meta.ts
+++ b/packages/backend/src/models/Meta.ts
@@ -665,12 +665,12 @@ export class MiMeta {
 	})
 	public googleAnalyticsMeasurementId: string | null;
 
-	@Column('boolean',{
+	@Column('boolean', {
 		default: false,
 	})
 	public enableLlmTranslator: boolean;
 
-	@Column('boolean',{
+	@Column('boolean', {
 		default: false,
 	})
 	public enableLlmTranslatorRedisCache: boolean;
diff --git a/packages/backend/src/server/api/endpoints/admin/update-meta.ts b/packages/backend/src/server/api/endpoints/admin/update-meta.ts
index 0327ee22a4..521814179f 100644
--- a/packages/backend/src/server/api/endpoints/admin/update-meta.ts
+++ b/packages/backend/src/server/api/endpoints/admin/update-meta.ts
@@ -187,15 +187,15 @@ export const paramDef = {
 		},
 		enableLlmTranslator: { type: 'boolean' },
 		enableLlmTranslatorRedisCache: { type: 'boolean' },
-		llmTranslatorRedisCacheTtl: { type: 'integer' , nullable: true},
-		llmTranslatorBaseUrl: { type: 'string' , nullable: true},
-		llmTranslatorApiKey: { type: 'string' , nullable: true},
-		llmTranslatorModel: { type: 'string' , nullable: true},
-		llmTranslatorTemperature: { type: 'number' , nullable: true},
-		llmTranslatorTopP: { type: 'number' , nullable: true},
-		llmTranslatorMaxTokens: { type: 'integer' , nullable: true},
-		llmTranslatorSysPrompt: { type: 'string' , nullable: true},
-		llmTranslatorUserPrompt: { type: 'string' , nullable: true},
+		llmTranslatorRedisCacheTtl: { type: 'integer' },
+		llmTranslatorBaseUrl: { type: 'string', nullable: true },
+		llmTranslatorApiKey: { type: 'string', nullable: true },
+		llmTranslatorModel: { type: 'string', nullable: true },
+		llmTranslatorTemperature: { type: 'number', nullable: true },
+		llmTranslatorTopP: { type: 'number', nullable: true },
+		llmTranslatorMaxTokens: { type: 'integer', nullable: true },
+		llmTranslatorSysPrompt: { type: 'string', nullable: true },
+		llmTranslatorUserPrompt: { type: 'string', nullable: true },
 	},
 	required: [],
 } as const;
diff --git a/packages/backend/src/server/api/endpoints/notes/translate.ts b/packages/backend/src/server/api/endpoints/notes/translate.ts
index 0fb32d3571..e85d063e0e 100644
--- a/packages/backend/src/server/api/endpoints/notes/translate.ts
+++ b/packages/backend/src/server/api/endpoints/notes/translate.ts
@@ -5,16 +5,16 @@
 
 import { URLSearchParams } from 'node:url';
 import { Inject, Injectable } from '@nestjs/common';
+import { OpenAI } from 'openai';
+import * as Redis from 'ioredis';
 import { Endpoint } from '@/server/api/endpoint-base.js';
 import { NoteEntityService } from '@/core/entities/NoteEntityService.js';
 import { HttpRequestService } from '@/core/HttpRequestService.js';
 import { GetterService } from '@/server/api/GetterService.js';
 import { RoleService } from '@/core/RoleService.js';
-import { ApiError } from '../../error.js';
 import { MiMeta } from '@/models/_.js';
 import { DI } from '@/di-symbols.js';
-import { OpenAI } from "openai";
-import * as Redis from 'ioredis';
+import { ApiError } from '../../error.js';
 
 export const meta = {
 	tags: ['notes'],
@@ -96,7 +96,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				const res = await this.llmTranslate(note.text, ps.targetLang, note.id);
 				return {
 					text: res,
-				}
+				};
 			}
 
 			if (this.serverSettings.deeplAuthKey == null) {
@@ -136,26 +136,24 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		});
 	}
 
-	private async llmTranslate(text: string, targetLang: string, noteId: string): Promise<string | null> {
+	private async llmTranslate(text: string, targetLang: string, noteId: string): Promise<string> {
 		if (this.serverSettings.enableLlmTranslatorRedisCache) {
 			const key = `llmTranslate:${targetLang}:${noteId}`;
 			const cached = await this.redisClient.get(key);
 			if (cached != null) {
-				this.redisClient.expire(key, this.serverSettings.llmTranslatorRedisCacheTtl*60);
+				this.redisClient.expire(key, this.serverSettings.llmTranslatorRedisCacheTtl * 60);
 				return cached;
 			}
 			const res = await this.getLlmRes(text, targetLang);
-			await this.redisClient.set(key, res ?? '');
-			this.redisClient.expire(key, this.serverSettings.llmTranslatorRedisCacheTtl*60);
+			await this.redisClient.set(key, res);
+			this.redisClient.expire(key, this.serverSettings.llmTranslatorRedisCacheTtl * 60);
 			return res;
-		}
-		else {
+		} else {
 			return this.getLlmRes(text, targetLang);
 		}
 	}
 
-
-	private async getLlmRes(text: string, targetLang: string): Promise<string | null> {
+	private async getLlmRes(text: string, targetLang: string): Promise<string> {
 		const client = new OpenAI({
 			baseURL: this.serverSettings.llmTranslatorBaseUrl,
 			apiKey: this.serverSettings.llmTranslatorApiKey ?? '',
@@ -173,8 +171,8 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 			temperature: this.serverSettings.llmTranslatorTemperature,
 			max_tokens: this.serverSettings.llmTranslatorMaxTokens,
 			top_p: this.serverSettings.llmTranslatorTopP,
-		})
+		});
 
-		return completion.choices[0].message.content
+		return completion.choices[0].message.content ?? '';
 	}
 }
diff --git a/packages/frontend/src/pages/admin/external-services.vue b/packages/frontend/src/pages/admin/external-services.vue
index 9c133641d3..1e84523a92 100644
--- a/packages/frontend/src/pages/admin/external-services.vue
+++ b/packages/frontend/src/pages/admin/external-services.vue
@@ -125,7 +125,6 @@ const llmTranslatorUserPrompt = ref<string>('');
 const llmTranslatorRedisCacheEnabled = ref<boolean>(false);
 const llmTranslatorRedisCacheTtl = ref<number>(0);
 
-
 async function init() {
 	const meta = await misskeyApi('admin/meta');
 	deeplAuthKey.value = meta.deeplAuthKey ?? '';