diff --git a/ui/package-lock.json b/ui/package-lock.json
index f3087d1bf98b..c9f90b6552a4 100644
--- a/ui/package-lock.json
+++ b/ui/package-lock.json
@@ -2816,6 +2816,12 @@
         "@types/node": "*"
       }
     },
+    "@types/trusted-types": {
+      "version": "2.0.7",
+      "resolved": "https://registry.npmjs.org/@types/trusted-types/-/trusted-types-2.0.7.tgz",
+      "integrity": "sha512-ScaPdn1dQczgbl0QFTeTOmVHFULt394XJgOQNoyVhZ6r2vLnMLJfBPd53SB52T/3G36VI1/g2MZaX0cwDuXsfw==",
+      "optional": true
+    },
     "@types/uglify-js": {
       "version": "3.16.0",
       "resolved": "https://registry.npmjs.org/@types/uglify-js/-/uglify-js-3.16.0.tgz",
@@ -9035,6 +9041,14 @@
         }
       }
     },
+    "dompurify": {
+      "version": "3.2.6",
+      "resolved": "https://registry.npmjs.org/dompurify/-/dompurify-3.2.6.tgz",
+      "integrity": "sha512-/2GogDQlohXPZe6D6NOgQvXLPSYBqIWMnZ8zzOhn09REE4eyAzb+Hed3jhoM9OkuaJ8P6ZGTTVWQKAi8ieIzfQ==",
+      "requires": {
+        "@types/trusted-types": "^2.0.7"
+      }
+    },
     "domutils": {
       "version": "1.7.0",
       "resolved": "https://registry.npmjs.org/domutils/-/domutils-1.7.0.tgz",
diff --git a/ui/package.json b/ui/package.json
index df8c5d5f82b7..3c7e1299a9d2 100644
--- a/ui/package.json
+++ b/ui/package.json
@@ -49,6 +49,7 @@
     "chartjs-adapter-moment": "^1.0.0",
     "core-js": "^3.21.1",
     "cronstrue": "^2.26.0",
+    "dompurify": "^3.2.6",
     "enquire.js": "^2.1.6",
     "js-cookie": "^2.2.1",
     "lodash": "^4.17.15",
diff --git a/ui/public/config.json b/ui/public/config.json
index 446256b5b189..d56e6f037831 100644
--- a/ui/public/config.json
+++ b/ui/public/config.json
@@ -100,5 +100,15 @@
   "imageSelectionInterface": "modern",
   "showUserCategoryForModernImageSelection": true,
   "showAllCategoryForModernImageSelection": false,
-  "docHelpMappings": {}
+  "docHelpMappings": {},
+  "announcementBanner": {
+    "enabled": false,
+    "showIcon": false,
+    "closable": true,
+    "persistDismissal": true,
+    "type": "info",
+    "message": "🤔 <strong>Sample Announcement</strong>: New Feature Available: Check out our latest dashboard improvements! <a href='/features'>Learn more</a>",
+    "startDate": "2025-06-01T00:00:00Z",
+    "endDate": "2025-07-16T00:00:00Z"
+  }
 }
diff --git a/ui/src/components/header/AnnouncementBanner.vue b/ui/src/components/header/AnnouncementBanner.vue
new file mode 100644
index 000000000000..af4a760c110a
--- /dev/null
+++ b/ui/src/components/header/AnnouncementBanner.vue
@@ -0,0 +1,145 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+<template>
+  <a-affix v-if="showBanner" class="announcement-banner-container">
+    <a-alert
+      :type="bannerConfig.type || 'default'"
+      :show-icon="bannerConfig.showIcon !== false"
+      :closable="bannerConfig.closable !== false"
+      :banner="true"
+      @close="handleClose"
+      :style="[ { border: borderColor }]"
+    >
+      <template #message>
+        <div class="banner-content" v-html="sanitizedMessage" :style="[$store.getters.darkMode ? { color: 'rgba(255, 255, 255, 0.65)' } : { color: '#888' }]" />
+      </template>
+    </a-alert>
+  </a-affix>
+</template>
+
+<script>
+import DOMPurify from 'dompurify'
+
+export default {
+  name: 'AnnouncementBanner',
+  data () {
+    return {
+      showBanner: false,
+      bannerConfig: {},
+      dismissed: false
+    }
+  },
+  computed: {
+    sanitizedMessage () {
+      if (!this.bannerConfig.message) return ''
+      const cleanHTML = DOMPurify.sanitize(this.bannerConfig.message, {
+        ALLOWED_TAGS: [
+          'p', 'div', 'span', 'br', 'strong', 'b', 'em', 'i', 'u',
+          'a', 'ul', 'ol', 'li', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6',
+          'small', 'mark', 'del', 'ins', 'sub', 'sup'
+        ],
+        ALLOWED_ATTR: ['href', 'target', 'rel', 'class', 'id', 'style'],
+        ALLOWED_URI_REGEXP: /^(?:(?:(?:f|ht)tps?|mailto|tel|callto|cid|xmpp|xxx):|[^a-z]|[a-z+.-]+(?:[^a-z+.\-:]|$))/i,
+        FORBID_TAGS: ['script', 'object', 'embed', 'form', 'input', 'textarea', 'select', 'button'],
+        FORBID_ATTR: ['onclick', 'onload', 'onerror', 'onmouseover', 'onfocus', 'onblur']
+      })
+      return cleanHTML
+    },
+    borderColor () {
+      const colorMap = {
+        error: '#ffa39e',
+        warning: '#ffe58f',
+        success: '#b7eb8f',
+        info: '#b3cde3'
+      }
+      const color = colorMap[this.bannerConfig.type]
+      return color ? `1px solid ${color}` : '0px'
+    }
+  },
+  mounted () {
+    this.loadBannerConfig()
+  },
+  methods: {
+    loadBannerConfig () {
+      const config = this.$config?.announcementBanner || {}
+      if (config && config.enabled && config.message) {
+        this.bannerConfig = config
+        if (config.persistDismissal) {
+          const dismissedKey = `cs-banner-dismissed-${this.getBannerHash()}`
+          this.dismissed = this.$localStorage.get(dismissedKey) === 'true'
+        }
+        if (!this.dismissed && this.isWithinDisplayPeriod()) {
+          this.showBanner = true
+        }
+      }
+    },
+    isWithinDisplayPeriod () {
+      const config = this.bannerConfig
+      const now = new Date()
+
+      if (config.startDate) {
+        const startDate = new Date(config.startDate)
+        if (now < startDate) return false
+      }
+
+      if (config.endDate) {
+        const endDate = new Date(config.endDate)
+        if (now > endDate) return false
+      }
+      return true
+    },
+    handleClose () {
+      this.showBanner = false
+      if (this.bannerConfig.persistDismissal) {
+        const dismissedKey = `cs-banner-dismissed-${this.getBannerHash()}`
+        this.$localStorage.set(dismissedKey, 'true')
+      }
+      if (this.bannerConfig.onClose) {
+        this.bannerConfig.onClose()
+      }
+    },
+    getBannerHash () {
+      // Create a simple hash of the message content for dismissal tracking
+      let hash = 0
+      const str = this.bannerConfig.message || ''
+      for (let i = 0; i < str.length; i++) {
+        const char = str.charCodeAt(i)
+        hash = ((hash << 5) - hash) + char
+        hash = hash & hash // Convert to 32bit integer
+      }
+      return Math.abs(hash).toString()
+    }
+  }
+}
+</script>
+
+<style scoped>
+.announcement-banner-container {
+  z-index: 1000;
+  top: 0;
+  margin: 0;
+  width: 100%;
+  justify-content: center;
+  align-items: center;
+}
+
+.banner-content {
+  line-height: 1.7;
+  text-align: center
+}
+</style>
diff --git a/ui/src/components/page/GlobalLayout.vue b/ui/src/components/page/GlobalLayout.vue
index 2002ca3bfc85..99a5707dc034 100644
--- a/ui/src/components/page/GlobalLayout.vue
+++ b/ui/src/components/page/GlobalLayout.vue
@@ -17,6 +17,7 @@
 
 <template>
   <div>
+    <announcement-banner />
     <a-affix v-if="this.$store.getters.maintenanceInitiated" >
       <a-alert :message="$t('message.maintenance.initiated')" type="error" banner :showIcon="false" class="maintenanceHeader" />
     </a-affix>
@@ -131,6 +132,7 @@ import { isAdmin } from '@/role'
 import { api } from '@/api'
 import Drawer from '@/components/widgets/Drawer'
 import Setting from '@/components/view/Setting.vue'
+import AnnouncementBanner from '@/components/header/AnnouncementBanner.vue'
 
 export default {
   name: 'GlobalLayout',
@@ -139,7 +141,8 @@ export default {
     GlobalHeader,
     GlobalFooter,
     Drawer,
-    Setting
+    Setting,
+    AnnouncementBanner
   },
   mixins: [mixin, mixinDevice],
   data () {
@@ -331,4 +334,8 @@ export default {
   position: absolute;
 }
 
+.layout.ant-layout .sidemenu .ant-header-fixedHeader {
+  top: auto !important
+}
+
 </style>
diff --git a/ui/src/main.js b/ui/src/main.js
index 3fee7428210b..d7f32ff503df 100644
--- a/ui/src/main.js
+++ b/ui/src/main.js
@@ -15,6 +15,7 @@
 // specific language governing permissions and limitations
 // under the License.
 
+import { createApp, h } from 'vue'
 import { vueApp, vueProps } from './vue-app'
 import router from './router'
 import store from './store'
@@ -60,20 +61,50 @@ vueApp.use(imagesUtilPlugin)
 vueApp.use(extensions)
 vueApp.use(directives)
 
-fetch('config.json?ts=' + Date.now()).then(response => response.json()).then(config => {
-  vueProps.$config = config
-  let basUrl = config.apiBase
-  if (config.multipleServer) {
-    basUrl = (config.servers[0].apiHost || '') + config.servers[0].apiBase
+const renderError = (err) => {
+  console.error('Fatal error during app initialization: ', err)
+  const ErrorComponent = {
+    render: () => h(
+      'div',
+      { style: 'font-family: sans-serif; text-align: center; padding: 2rem;' },
+      [
+        h('h2', { style: 'color: #ff4d4f;' }, 'We\'re experiencing a problem'),
+        h('p', 'The application could not be loaded due to a configuration issue. Please try again later.'),
+        h('details', { style: 'margin-top: 20px;' }, [
+          h('summary', { style: 'cursor: pointer;' }, 'Technical details'),
+          h('pre', {
+            style: 'text-align: left; display: inline-block; margin-top: 10px;'
+          }, 'Missing or malformed config.json. Please ensure the file is present, accessible, and contains valid JSON. Check the browser console for more information.')
+        ])
+      ]
+    )
   }
+  createApp(ErrorComponent).mount('#app')
+}
 
-  vueProps.axios.defaults.baseURL = basUrl
+fetch('config.json?ts=' + Date.now())
+  .then(response => {
+    if (!response.ok) {
+      throw new Error(`Failed to fetch config.json: ${response.status} ${response.statusText}`)
+    }
+    return response.json()
+  })
+  .then(config => {
+    vueProps.$config = config
+    let baseUrl = config.apiBase
+    if (config.multipleServer) {
+      baseUrl = (config.servers[0].apiHost || '') + config.servers[0].apiBase
+    }
+
+    vueProps.axios.defaults.baseURL = baseUrl
 
-  loadLanguageAsync().then(() => {
-    vueApp.use(store)
-      .use(router)
-      .use(i18n)
-      .use(bootstrap)
-      .mount('#app')
+    loadLanguageAsync().then(() => {
+      vueApp.use(store)
+        .use(router)
+        .use(i18n)
+        .use(bootstrap)
+        .mount('#app')
+    })
+  }).catch(error => {
+    renderError(error)
   })
-})