diff --git a/internal/web/static/upload.js b/internal/web/static/upload.js
index 142971d..a89edb3 100644
--- a/internal/web/static/upload.js
+++ b/internal/web/static/upload.js
@@ -306,7 +306,10 @@ class GatewayUI {
             // Set timeout (10 minutes for large files)
             xhr.timeout = 600000;
             
-            // Set headers
+            // Open connection FIRST
+            xhr.open(options.method || 'GET', url);
+            
+            // Set headers AFTER opening
             Object.entries(options.headers || {}).forEach(([key, value]) => {
                 xhr.setRequestHeader(key, value);
             });
@@ -319,7 +322,6 @@ class GatewayUI {
             }
             
             // Send request
-            xhr.open(options.method || 'GET', url);
             xhr.send(options.body);
         });
     }