diff --git a/weed/admin/static/js/admin.js b/weed/admin/static/js/admin.js
index 2633cb5b2..1160790b5 100644
--- a/weed/admin/static/js/admin.js
+++ b/weed/admin/static/js/admin.js
@@ -1267,7 +1267,7 @@ async function submitUploadFile() {
         });
 
         // Send request
-        xhr.open('POST', '/api/files/upload');
+        xhr.open('POST', basePath('/api/files/upload'));
         xhr.send(formData);
 
     } catch (error) {
@@ -1320,7 +1320,7 @@ function exportFileList() {
 // Download file
 function downloadFile(filePath) {
     // Create download link using admin API
-    const downloadUrl = `/api/files/download?path=${encodeURIComponent(filePath)}`;
+    const downloadUrl = basePath(`/api/files/download?path=${encodeURIComponent(filePath)}`);
     window.open(downloadUrl, '_blank');
 }
 
@@ -1786,7 +1786,7 @@ function createFileViewerContent(file, content) {
     if (file.mime.startsWith('image/')) {
         return `
             <div class="text-center">
-                <img src="/api/files/download?path=${encodeURIComponent(file.full_path)}" 
+                <img src="${basePath('/api/files/download?path=' + encodeURIComponent(file.full_path))}"
                      class="img-fluid" alt="${file.name}" style="max-height: 500px;">
             </div>
         `;
@@ -1804,7 +1804,7 @@ function createFileViewerContent(file, content) {
     } else if (file.mime === 'application/pdf') {
         return `
             <div class="text-center">
-                <embed src="/api/files/download?path=${encodeURIComponent(file.full_path)}" 
+                <embed src="${basePath('/api/files/download?path=' + encodeURIComponent(file.full_path))}"
                        type="application/pdf" width="100%" height="500px">
             </div>
         `;
diff --git a/weed/command/admin.go b/weed/command/admin.go
index fca5524e1..31ddd7a2c 100644
--- a/weed/command/admin.go
+++ b/weed/command/admin.go
@@ -392,7 +392,19 @@ func startAdminServer(ctx context.Context, options AdminOptions, enableUI bool,
 	addr := fmt.Sprintf(":%d", *options.port)
 	var handler http.Handler = r
 	if urlPrefix != "" {
-		handler = http.StripPrefix(urlPrefix, r)
+		stripped := http.StripPrefix(urlPrefix, r)
+		handler = http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+			// Redirect /prefix (no trailing slash) to /prefix/
+			if req.URL.Path == urlPrefix {
+				target := urlPrefix + "/"
+				if req.URL.RawQuery != "" {
+					target += "?" + req.URL.RawQuery
+				}
+				http.Redirect(w, req, target, http.StatusFound)
+				return
+			}
+			stripped.ServeHTTP(w, req)
+		})
 	}
 	server := &http.Server{
 		Addr:    addr,