diff --git a/main.py b/main.py
index 9f62fdf410..907d922188 100644
--- a/main.py
+++ b/main.py
@@ -79,25 +79,38 @@ async def check_dashboard_files(webui_dir: str | None = None):
 
     data_dist_path = os.path.join(get_astrbot_data_path(), "dist")
     if os.path.exists(data_dist_path):
-        v = await get_dashboard_version()
-        if should_use_bundled_dashboard_dist(data_dist_path, VERSION):
-            bundled_dist = get_bundled_dashboard_dist_path()
-            logger.info(
-                "Using bundled WebUI because data/dist is older than core version v%s.",
-                VERSION,
+        index_html = os.path.join(data_dist_path, "index.html")
+        assets_dir = os.path.join(data_dist_path, "assets")
+        version_file = os.path.join(assets_dir, "version")
+        if not (
+            os.path.isfile(index_html)
+            and os.path.isdir(assets_dir)
+            and os.path.isfile(version_file)
+        ):
+            logger.warning(
+                "WebUI directory is incomplete: %s. Downloading a fresh copy.",
+                data_dist_path,
             )
-            return str(bundled_dist)
-        if v is not None:
-            # 存在文件
-            if v == f"v{VERSION}":
-                logger.info("WebUI is up to date.")
-            else:
-                logger.warning(
-                    "WebUI version mismatch: %s, expected v%s.",
-                    v,
+        else:
+            v = await get_dashboard_version()
+            if should_use_bundled_dashboard_dist(data_dist_path, VERSION):
+                bundled_dist = get_bundled_dashboard_dist_path()
+                logger.info(
+                    "Using bundled WebUI because data/dist is older than core version v%s.",
                     VERSION,
                 )
-        return data_dist_path
+                return str(bundled_dist)
+            if v is not None:
+                # 存在文件
+                if v == f"v{VERSION}":
+                    logger.info("WebUI is up to date.")
+                else:
+                    logger.warning(
+                        "WebUI version mismatch: %s, expected v%s.",
+                        v,
+                        VERSION,
+                    )
+            return data_dist_path
 
     logger.info(
         "Downloading WebUI. If it fails, download dist.zip from https://github.com/AstrBotDevs/AstrBot/releases/latest and extract dist to data/.",
diff --git a/tests/test_main.py b/tests/test_main.py
index ae60366315..1b681c27b6 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -10,7 +10,7 @@
 import pytest
 
 from astrbot.core.utils.io import should_use_bundled_dashboard_dist
-from main import check_dashboard_files, check_env
+from main import VERSION, check_dashboard_files, check_env
 
 
 class _version_info:
@@ -158,6 +158,8 @@ async def test_check_dashboard_files_exists_and_version_match(monkeypatch):
     """Tests that dashboard is not downloaded when it exists and version matches."""
     # Mock os.path.exists to return True
     monkeypatch.setattr(os.path, "exists", lambda x: True)
+    monkeypatch.setattr(os.path, "isfile", lambda x: True)
+    monkeypatch.setattr(os.path, "isdir", lambda x: True)
 
     # Mock get_dashboard_version to return the current version
     with mock.patch("main.get_dashboard_version") as mock_get_version:
@@ -176,6 +178,8 @@ async def test_check_dashboard_files_exists_and_version_match(monkeypatch):
 async def test_check_dashboard_files_exists_but_version_mismatch(monkeypatch):
     """Tests that a warning is logged when dashboard version mismatches."""
     monkeypatch.setattr(os.path, "exists", lambda x: True)
+    monkeypatch.setattr(os.path, "isfile", lambda x: True)
+    monkeypatch.setattr(os.path, "isdir", lambda x: True)
 
     with mock.patch(
         "main.get_dashboard_version", mock.AsyncMock(return_value="v0.0.1")
@@ -225,6 +229,9 @@ async def test_check_dashboard_files_uses_bundled_dist_when_data_dist_is_stale(
     data_dist = data_dir / "dist"
     bundled_dist = tmp_path / "bundled-dist"
     data_dist.mkdir(parents=True)
+    (data_dist / "index.html").write_text("", encoding="utf-8")
+    (data_dist / "assets").mkdir()
+    (data_dist / "assets" / "version").write_text("v0.0.1", encoding="utf-8")
     bundled_dist.mkdir()
 
     with mock.patch("main.get_astrbot_data_path", return_value=str(data_dir)):
@@ -245,6 +252,25 @@ async def test_check_dashboard_files_uses_bundled_dist_when_data_dist_is_stale(
     mock_download.assert_not_called()
 
 
+@pytest.mark.asyncio
+async def test_check_dashboard_files_redownloads_incomplete_data_dist(tmp_path):
+    """Tests that a partial data/dist does not skip dashboard download."""
+    data_dir = tmp_path / "data"
+    data_dist = data_dir / "dist"
+    data_dist.mkdir(parents=True)
+
+    with mock.patch("main.get_astrbot_data_path", return_value=str(data_dir)):
+        with mock.patch("main.get_dashboard_version") as mock_get_version:
+            with mock.patch(
+                "main.download_dashboard", mock.AsyncMock()
+            ) as mock_download:
+                result = await check_dashboard_files()
+
+    assert result == str(data_dist)
+    mock_get_version.assert_not_called()
+    mock_download.assert_awaited_once_with(version=f"v{VERSION}", latest=False)
+
+
 @pytest.mark.asyncio
 async def test_check_dashboard_files_with_webui_dir_arg(monkeypatch):
     """Tests that providing a valid webui_dir skips all checks."""