diff --git a/bin/hermes-web-ui.mjs b/bin/hermes-web-ui.mjs
index 85c8af8..f3f41e6 100755
--- a/bin/hermes-web-ui.mjs
+++ b/bin/hermes-web-ui.mjs
@@ -1,6 +1,6 @@
 #!/usr/bin/env node
-import { spawn, execSync } from 'child_process'
-import { resolve, dirname, join } from 'path'
+import { spawn, execSync, execFileSync } from 'child_process'
+import { resolve, dirname, join, delimiter } from 'path'
 import { fileURLToPath } from 'url'
 import { readFileSync, writeFileSync, unlinkSync, mkdirSync, openSync, chmodSync, statSync, existsSync } from 'fs'
 import { randomBytes } from 'crypto'
@@ -56,8 +56,27 @@ function getNpmBin() {
   return join(getNodeBinDir(), process.platform === 'win32' ? 'npm.cmd' : 'npm')
 }
 
-function getCliBin() {
-  return join(getNodeBinDir(), process.platform === 'win32' ? 'hermes-web-ui.cmd' : 'hermes-web-ui')
+function getCurrentNodeEnv() {
+  return {
+    ...process.env,
+    PATH: [getNodeBinDir(), process.env.PATH].filter(Boolean).join(delimiter),
+    npm_node_execpath: process.execPath,
+  }
+}
+
+function getGlobalPrefix() {
+  return execFileSync(getNpmBin(), ['prefix', '-g'], {
+    encoding: 'utf-8',
+    stdio: ['pipe', 'pipe', 'pipe'],
+    env: getCurrentNodeEnv(),
+  }).trim()
+}
+
+function getGlobalCliBin() {
+  const prefix = getGlobalPrefix()
+  return process.platform === 'win32'
+    ? join(prefix, 'hermes-web-ui.cmd')
+    : join(prefix, 'bin', 'hermes-web-ui')
 }
 
 function getWindowsShell() {
@@ -431,18 +450,36 @@ function doUpdate() {
   const child = spawnCli(getNpmBin(), ['install', '-g', 'hermes-web-ui@latest'], {
     stdio: 'inherit',
     windowsHide: true,
+    env: getCurrentNodeEnv(),
+  })
+
+  child.on('error', (err) => {
+    console.log(`  ✗ Update failed: ${err.message}`)
+    process.exit(1)
   })
 
   child.on('exit', (code) => {
     if (code === 0) {
       console.log('  ✓ Update complete, restarting...')
-      const restart = spawnCli(getCliBin(), ['restart', '--port', String(getUpdatePort())], {
+      const cli = getGlobalCliBin()
+      if (!existsSync(cli)) {
+        console.log(`  ✗ Updated CLI not found: ${cli}`)
+        process.exit(1)
+      }
+
+      const restart = spawnCli(cli, ['restart', '--port', String(getUpdatePort())], {
         stdio: 'inherit',
         windowsHide: true,
+        env: getCurrentNodeEnv(),
+      })
+      restart.on('error', (err) => {
+        console.log(`  ✗ Restart failed: ${err.message}`)
+        process.exit(1)
       })
       restart.on('exit', (restartCode) => process.exit(restartCode ?? 1))
     } else {
       console.log('  ✗ Update failed')
+      process.exit(code ?? 1)
     }
   })
 }
diff --git a/package.json b/package.json
index a29a85b..ae3db0a 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "hermes-web-ui",
-  "version": "0.5.20",
+  "version": "0.5.21",
   "description": "Self-hosted AI chat dashboard for Hermes Agent — multi-model web UI with multi-platform integration",
   "repository": {
     "type": "git",
diff --git a/packages/client/src/data/changelog.ts b/packages/client/src/data/changelog.ts
index 3134124..4cca838 100644
--- a/packages/client/src/data/changelog.ts
+++ b/packages/client/src/data/changelog.ts
@@ -6,7 +6,7 @@ export interface ChangelogEntry {
 
 export const changelog: ChangelogEntry[] = [
   {
-    version: '0.5.20',
+    version: '0.5.21',
     date: '2026-05-14',
     changes: [
       'changelog.new_0_5_18_1',
diff --git a/packages/client/src/i18n/locales/de.ts b/packages/client/src/i18n/locales/de.ts
index 98fa6b9..11e2469 100644
--- a/packages/client/src/i18n/locales/de.ts
+++ b/packages/client/src/i18n/locales/de.ts
@@ -92,7 +92,7 @@ export default {
     updateVersion: 'Aktualisieren auf v{version}',
     reloadClientVersion: 'Für v{version} neu laden',
     updating: 'Aktualisierung...',
-    updateSuccess: 'Aktualisierung abgeschlossen, bitte Server neu starten',
+    updateSuccess: 'Aktualisierung erfolgreich. Bitte aktualisieren Sie die Seite in Kurze. Wenn der Dienst langere Zeit nicht startet, starten Sie ihn manuell.',
     updateFailed: 'Aktualisierung fehlgeschlagen',
     logout: 'Abmelden',
     nodeVersionWarning: 'Node.js v{version} erkannt. Bitte aktualisieren Sie auf Version 23 oder neuer.',
diff --git a/packages/client/src/i18n/locales/en.ts b/packages/client/src/i18n/locales/en.ts
index 01869b9..eadd5c5 100644
--- a/packages/client/src/i18n/locales/en.ts
+++ b/packages/client/src/i18n/locales/en.ts
@@ -104,7 +104,7 @@ export default {
     updateVersion: 'Upgrade to v{version}',
     reloadClientVersion: 'Reload for v{version}',
     updating: 'Updating...',
-    updateSuccess: 'Update complete, please restart the server',
+    updateSuccess: 'Update successful. Please refresh the page shortly. If it does not start after a while, start it manually.',
     updateFailed: 'Update failed',
     logout: 'Sign Out',
     nodeVersionWarning: 'Detected Node.js v{version}. Please upgrade to version 23 or later.',
diff --git a/packages/client/src/i18n/locales/es.ts b/packages/client/src/i18n/locales/es.ts
index 0b23d3c..6f73d36 100644
--- a/packages/client/src/i18n/locales/es.ts
+++ b/packages/client/src/i18n/locales/es.ts
@@ -92,7 +92,7 @@ export default {
     updateVersion: 'Actualizar a v{version}',
     reloadClientVersion: 'Recargar para v{version}',
     updating: 'Actualizando...',
-    updateSuccess: 'Actualizacion completa, por favor reinicia el servidor',
+    updateSuccess: 'Actualizacion completada. Actualiza la pagina en breve. Si no se inicia despues de un tiempo, inicialo manualmente.',
     updateFailed: 'Error al actualizar',
     logout: 'Cerrar sesion',
     nodeVersionWarning: 'Se detecto Node.js v{version}. Actualiza a la version 23 o posterior.',
diff --git a/packages/client/src/i18n/locales/fr.ts b/packages/client/src/i18n/locales/fr.ts
index 7a36771..8872776 100644
--- a/packages/client/src/i18n/locales/fr.ts
+++ b/packages/client/src/i18n/locales/fr.ts
@@ -92,7 +92,7 @@ export default {
     updateVersion: 'Mettre a jour vers v{version}',
     reloadClientVersion: 'Recharger pour v{version}',
     updating: 'Mise a jour...',
-    updateSuccess: 'Mise a jour terminee, veuillez redemarrer le serveur',
+    updateSuccess: 'Mise a jour terminee. Veuillez actualiser la page sous peu. Si le service ne demarre pas apres un moment, demarrez-le manuellement.',
     updateFailed: 'Echec de la mise a jour',
     logout: 'Deconnexion',
     nodeVersionWarning: 'Node.js v{version} detecte. Veuillez passer a la version 23 ou ulterieure.',
diff --git a/packages/client/src/i18n/locales/ja.ts b/packages/client/src/i18n/locales/ja.ts
index 1bbaf25..08697af 100644
--- a/packages/client/src/i18n/locales/ja.ts
+++ b/packages/client/src/i18n/locales/ja.ts
@@ -92,7 +92,7 @@ export default {
     updateVersion: 'v{version} にアップグレード',
     reloadClientVersion: 'v{version} に再読み込み',
     updating: '更新中...',
-    updateSuccess: '更新が完了しました。サーバーを再起動してください',
+    updateSuccess: '更新が完了しました。しばらくしてからページを再読み込みしてください。長時間起動しない場合は手動で起動してください。',
     updateFailed: '更新に失敗しました',
     logout: 'ログアウト',
     nodeVersionWarning: 'Node.js v{version} が検出されました。バージョン23以降にアップグレードしてください。',
diff --git a/packages/client/src/i18n/locales/ko.ts b/packages/client/src/i18n/locales/ko.ts
index 7de6dc9..1eb0625 100644
--- a/packages/client/src/i18n/locales/ko.ts
+++ b/packages/client/src/i18n/locales/ko.ts
@@ -92,7 +92,7 @@ export default {
     updateVersion: 'v{version}(으)로 업그레이드',
     reloadClientVersion: 'v{version}(으)로 새로고침',
     updating: '업데이트 중...',
-    updateSuccess: '업데이트 완료, 서버를 재시작해 주세요',
+    updateSuccess: '업데이트가 완료되었습니다. 잠시 후 페이지를 새로고침하세요. 오랫동안 시작되지 않으면 수동으로 시작하세요.',
     updateFailed: '업데이트 실패',
     logout: '로그아웃',
     nodeVersionWarning: 'Node.js v{version}이 감지되었습니다. 버전 23 이상으로 업그레이드하세요.',
diff --git a/packages/client/src/i18n/locales/pt.ts b/packages/client/src/i18n/locales/pt.ts
index 7d0472c..870f7fc 100644
--- a/packages/client/src/i18n/locales/pt.ts
+++ b/packages/client/src/i18n/locales/pt.ts
@@ -92,7 +92,7 @@ export default {
     updateVersion: 'Atualizar para v{version}',
     reloadClientVersion: 'Recarregar para v{version}',
     updating: 'Atualizando...',
-    updateSuccess: 'Atualizacao concluida, por favor reinicie o servidor',
+    updateSuccess: 'Atualizacao concluida. Atualize a pagina em breve. Se nao iniciar apos algum tempo, inicie manualmente.',
     updateFailed: 'Falha na atualizacao',
     logout: 'Sair',
     nodeVersionWarning: 'Node.js v{version} detectado. Atualize para a versao 23 ou posterior.',
diff --git a/packages/client/src/i18n/locales/zh-TW.ts b/packages/client/src/i18n/locales/zh-TW.ts
index cb4d77b..77b2861 100644
--- a/packages/client/src/i18n/locales/zh-TW.ts
+++ b/packages/client/src/i18n/locales/zh-TW.ts
@@ -104,7 +104,7 @@ export default {
     updateVersion: '升級版本 v{version}',
     reloadClientVersion: '重新整理到 v{version}',
     updating: '正在更新...',
-    updateSuccess: '更新完成，請重新啟動服務',
+    updateSuccess: '更新成功，請稍後重新整理頁面，如長時間未啟動，請手動啟動',
     updateFailed: '更新失敗',
     logout: '登出',
     nodeVersionWarning: '偵測到 Node.js v{version}，請升級至 23 以上版本。',
diff --git a/packages/client/src/i18n/locales/zh.ts b/packages/client/src/i18n/locales/zh.ts
index 2af7459..3aee9ba 100644
--- a/packages/client/src/i18n/locales/zh.ts
+++ b/packages/client/src/i18n/locales/zh.ts
@@ -104,7 +104,7 @@ export default {
     updateVersion: '升级版本 v{version}',
     reloadClientVersion: '刷新到 v{version}',
     updating: '正在更新...',
-    updateSuccess: '更新完成，请重启服务',
+    updateSuccess: '更新成功，请稍后刷新页面，如长时间未启动，请手动启动',
     updateFailed: '更新失败',
     logout: '退出登录',
     nodeVersionWarning: '检测到 Node.js v{version}，请升级到23以上版本。',
diff --git a/packages/server/src/controllers/update.ts b/packages/server/src/controllers/update.ts
index c61a626..4e80d5d 100644
--- a/packages/server/src/controllers/update.ts
+++ b/packages/server/src/controllers/update.ts
@@ -2,6 +2,8 @@ import { execFileSync, spawn } from 'child_process'
 import { existsSync } from 'fs'
 import { delimiter, dirname, join } from 'path'
 
+let updateInProgress = false
+
 function getNodeBinDir() {
   return dirname(process.execPath)
 }
@@ -10,27 +12,39 @@ function getNodePrefix() {
   return process.platform === 'win32' ? getNodeBinDir() : dirname(getNodeBinDir())
 }
 
-function getNpmCliPath() {
+function getHomebrewPrefix() {
+  const match = process.execPath.match(/^(.*)\/Cellar\/[^/]+\/[^/]+\/bin\/node$/)
+  return match?.[1] || null
+}
+
+function getNpmCliCandidates() {
   const prefix = getNodePrefix()
-  const candidates = process.platform === 'win32'
+  const homebrewPrefix = getHomebrewPrefix()
+
+  return process.platform === 'win32'
     ? [
         join(prefix, 'node_modules', 'npm', 'bin', 'npm-cli.js'),
         join(getNodeBinDir(), 'node_modules', 'npm', 'bin', 'npm-cli.js'),
       ]
-    : [join(prefix, 'lib', 'node_modules', 'npm', 'bin', 'npm-cli.js')]
-  const npmCli = candidates.find(existsSync)
-
-  if (!npmCli) {
-    throw new Error(`Unable to locate npm CLI for ${process.execPath}; checked ${candidates.join(', ')}`)
-  }
-
-  return npmCli
+    : [
+        join(prefix, 'lib', 'node_modules', 'npm', 'bin', 'npm-cli.js'),
+        ...(homebrewPrefix ? [join(homebrewPrefix, 'lib', 'node_modules', 'npm', 'bin', 'npm-cli.js')] : []),
+      ]
 }
 
-function getGlobalPackageBin(prefix: string) {
-  return process.platform === 'win32'
-    ? join(prefix, 'node_modules', 'hermes-web-ui', 'bin', 'hermes-web-ui.mjs')
-    : join(prefix, 'lib', 'node_modules', 'hermes-web-ui', 'bin', 'hermes-web-ui.mjs')
+function getNpmCliPath() {
+  const candidates = getNpmCliCandidates()
+  const npmCli = candidates.find(existsSync)
+
+  return npmCli || null
+}
+
+function getNpmBin() {
+  return process.platform === 'win32' ? 'npm.cmd' : 'npm'
+}
+
+function getGlobalPackageBin(root: string) {
+  return join(root, 'hermes-web-ui', 'bin', 'hermes-web-ui.mjs')
 }
 
 function getCurrentNodeEnv() {
@@ -42,7 +56,11 @@ function getCurrentNodeEnv() {
 }
 
 function runNpm(args: string[], options: { timeout?: number } = {}) {
-  return execFileSync(process.execPath, [getNpmCliPath(), ...args], {
+  const npmCli = getNpmCliPath()
+  const command = npmCli ? process.execPath : getNpmBin()
+  const commandArgs = npmCli ? [npmCli, ...args] : args
+
+  return execFileSync(command, commandArgs, {
     encoding: 'utf-8',
     timeout: options.timeout,
     stdio: ['pipe', 'pipe', 'pipe'],
@@ -50,12 +68,16 @@ function runNpm(args: string[], options: { timeout?: number } = {}) {
   }).trim()
 }
 
-function getGlobalPrefix() {
-  return runNpm(['prefix', '-g'])
+function getGlobalRoot() {
+  return runNpm(['root', '-g'])
 }
 
 function getGlobalCliScript() {
-  return getGlobalPackageBin(getGlobalPrefix())
+  const cli = getGlobalPackageBin(getGlobalRoot())
+  if (!existsSync(cli)) {
+    throw new Error(`Updated hermes-web-ui CLI not found: ${cli}`)
+  }
+  return cli
 }
 
 function runUpdateInstall() {
@@ -74,6 +96,17 @@ function spawnRestart(port: string) {
 }
 
 export async function handleUpdate(ctx: any) {
+  if (updateInProgress) {
+    ctx.status = 409
+    ctx.body = {
+      success: false,
+      message: 'hermes-web-ui update is already in progress',
+    }
+    return
+  }
+
+  updateInProgress = true
+
   try {
     const output = runUpdateInstall()
 
@@ -83,13 +116,27 @@ export async function handleUpdate(ctx: any) {
     }
 
     setTimeout(() => {
+      let restart
       try {
-        spawnRestart(process.env.PORT || '8648').unref()
-      } finally {
-        process.exit(0)
+        restart = spawnRestart(process.env.PORT || '8648')
+      } catch (err) {
+        updateInProgress = false
+        console.error('[update] failed to spawn restart:', err)
+        return
       }
+
+      restart.on('error', (err) => {
+        updateInProgress = false
+        console.error('[update] restart process failed:', err)
+      })
+      restart.on('exit', (code, signal) => {
+        updateInProgress = false
+        console.error(`[update] restart process exited before replacing server: code=${code} signal=${signal}`)
+      })
+      restart.unref()
     }, 3000)
   } catch (err: any) {
+    updateInProgress = false
     ctx.status = 500
     ctx.body = {
       success: false,