diff --git a/packages/backend/src/boot/entry.ts b/packages/backend/src/boot/entry.ts
index 2bf67207b9..7c788cc625 100644
--- a/packages/backend/src/boot/entry.ts
+++ b/packages/backend/src/boot/entry.ts
@@ -71,7 +71,7 @@ if (!envOption.quiet) {
 // Display detail of uncaught exception
 process.on('uncaughtException', err => {
 	try {
-		logger.error('Uncaught exception', { error: err });
+		logger.error(`Uncaught exception: ${err.message}`, { error: err });
 	} catch { }
 });
 
diff --git a/packages/backend/src/logger.ts b/packages/backend/src/logger.ts
index 1d442cd65b..e3283b6866 100644
--- a/packages/backend/src/logger.ts
+++ b/packages/backend/src/logger.ts
@@ -4,6 +4,7 @@
  */
 
 import cluster from 'node:cluster';
+import util from 'node:util';
 import chalk from 'chalk';
 import { default as convertColor } from 'color-convert';
 import { format as dateFormat } from 'date-fns';
@@ -11,6 +12,34 @@ import { bindThis } from '@/decorators.js';
 import { envOption } from './env.js';
 import type { KEYWORD } from 'color-convert/conversions.js';
 
+util.inspect.defaultOptions = envOption.logJson ? {
+	showHidden: false,
+	depth: null,
+	colors: false,
+	customInspect: true,
+	showProxy: false,
+	maxArrayLength: null,
+	maxStringLength: null,
+	breakLength: Infinity,
+	compact: true,
+	sorted: false,
+	getters: false,
+	numericSeparator: false,
+} : {
+	showHidden: false,
+	depth: null,
+	colors: true,
+	customInspect: true,
+	showProxy: false,
+	maxArrayLength: null,
+	maxStringLength: null,
+	breakLength: Infinity,
+	compact: true,
+	sorted: false,
+	getters: false,
+	numericSeparator: false,
+};
+
 type Context = {
 	name: string;
 	color?: KEYWORD;
@@ -18,6 +47,13 @@ type Context = {
 
 type Level = 'error' | 'success' | 'warning' | 'debug' | 'info';
 
+function inspect(_: string, value: any): null | string | number | boolean {
+	if (value === null || value === undefined) return null;
+	if (typeof value === 'string' || typeof value === 'number' || typeof value === 'boolean') return value;
+	if (value instanceof Date) return value.toISOString();
+	return util.inspect(value);
+}
+
 // eslint-disable-next-line import/no-default-export
 export default class Logger {
 	private context: Context;
@@ -59,7 +95,7 @@ export default class Logger {
 				important: important,
 				context: [this.context].concat(subContexts).map(d => d.name).join('.'),
 				cluster: cluster.isPrimary ? 'primary' : `worker-${cluster.worker!.id}`,
-			}));
+			}, inspect));
 			return;
 		}
 
@@ -86,7 +122,7 @@ export default class Logger {
 
 		const args: unknown[] = [important ? chalk.bold(log) : log];
 		if (data != null) {
-			args.push(data);
+			args.push(JSON.stringify(data, inspect, 2));
 		}
 
 		if (level === 'error' || level === 'warning') {
diff --git a/packages/backend/src/server/api/endpoints/admin/emoji/copy.ts b/packages/backend/src/server/api/endpoints/admin/emoji/copy.ts
index 91d9e4b6a4..2dfa95d303 100644
--- a/packages/backend/src/server/api/endpoints/admin/emoji/copy.ts
+++ b/packages/backend/src/server/api/endpoints/admin/emoji/copy.ts
@@ -77,8 +77,20 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				// Create file
 				driveFile = await this.driveService.uploadFromUrl({ url: emoji.originalUrl, user: null, force: true });
 			} catch (e) {
-				// TODO: need to return Drive Error
-				throw new ApiError();
+				const err = e as Error;
+				throw new ApiError(
+					{
+						message: 'Failed to upload image from URL.',
+						code: 'FAILED_TO_UPLOAD_IMAGE_FROM_URL',
+						id: '5c77c4d7-0f68-48f9-8694-8453a2294840',
+					},
+					{
+						e: {
+							message: err.message,
+							code: err.name,
+						}
+					}
+				);
 			}
 
 			// Duplication Check
diff --git a/packages/backend/src/server/api/endpoints/drive/files/create.ts b/packages/backend/src/server/api/endpoints/drive/files/create.ts
index 59eff00370..34fc637ab4 100644
--- a/packages/backend/src/server/api/endpoints/drive/files/create.ts
+++ b/packages/backend/src/server/api/endpoints/drive/files/create.ts
@@ -113,13 +113,26 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 					requestHeaders: instance.enableIpLogging ? headers : null,
 				});
 				return await this.driveFileEntityService.pack(driveFile, me, { self: true });
-			} catch (err) {
-				this.logger.error('Failed to create drive file', { error: err });
-				if (err instanceof IdentifiableError) {
-					if (err.id === '282f77bf-5816-4f72-9264-aa14d8261a21') throw new ApiError(meta.errors.inappropriate);
-					if (err.id === 'c6244ed2-a39a-4e1c-bf93-f0fbd7764fa6') throw new ApiError(meta.errors.noFreeSpace);
+			} catch (e) {
+				this.logger.error('Failed to create drive file', { error: e });
+				if (e instanceof IdentifiableError) {
+					if (e.id === '282f77bf-5816-4f72-9264-aa14d8261a21') throw new ApiError(meta.errors.inappropriate);
+					if (e.id === 'c6244ed2-a39a-4e1c-bf93-f0fbd7764fa6') throw new ApiError(meta.errors.noFreeSpace);
 				}
-				throw new ApiError();
+				const err = e as Error;
+				throw new ApiError(
+					{
+						message: 'Failed to create drive file.',
+						code: 'FAILED_TO_CREATE_DRIVE_FILE',
+						id: '6708863c-6791-4487-aa01-2d682c6e7db0',
+					},
+					{
+						e: {
+							message: err.message,
+							code: err.name,
+						}
+					}
+				);
 			} finally {
 				cleanup!();
 			}