diff --git a/src/slic3r/GUI/MainFrame.cpp b/src/slic3r/GUI/MainFrame.cpp
index 5db1ead689..b8b78ce273 100644
--- a/src/slic3r/GUI/MainFrame.cpp
+++ b/src/slic3r/GUI/MainFrame.cpp
@@ -3921,8 +3921,17 @@ void MainFrame::downloadOpenProject(const std::string& fileUrl, const std::strin
 {
     // std::string fileUrl = "https://public.resource.snapmaker.com/model/public/3mf/test_for_download.3mf";
     // std::string           filename     = "test_for_download.3mf";
+    wxString fileNameEx = wxString::FromUTF8(fileName.c_str()).Lower();
+    std::string releaFileName = "";
 
-    GenericDownloadDialog dlg(_L("downloading the model"), fileUrl, fileName, completeFilePath);
+    bool strRes = fileNameEx.EndsWith(".3mf");
+
+    if (strRes)
+        releaFileName = fileName;
+    else
+        releaFileName = fileName + ".3mf";
+
+    GenericDownloadDialog dlg(_L("downloading the model"), fileUrl, releaFileName, completeFilePath);
     auto res = dlg.ShowModal();
 
     if (res != wxID_OK)
@@ -3930,7 +3939,7 @@ void MainFrame::downloadOpenProject(const std::string& fileUrl, const std::strin
 
     if (completeFilePath.empty()) {
         auto downloadPath = wxGetApp().app_config->get("download_path");
-        completeFilePath  = downloadPath + "/" + fileName;
+        completeFilePath  = downloadPath + "/" + releaFileName;
     }
     if (!boost::filesystem::exists(completeFilePath)) 
     {
@@ -3951,7 +3960,7 @@ void MainFrame::downloadOpenProject(const std::string& fileUrl, const std::strin
     else
     {
         // Not a valid 3mf file, show error message
-        wxString msg = wxString::Format(_L("The downloaded file '%s' is not a valid 3MF project file."), fileName);
+        wxString msg = wxString::Format(_L("The downloaded file '%s' is not a valid 3MF project file."), releaFileName);
         MessageDialog(this, msg, _L("Invalid File"), wxOK | wxICON_WARNING).ShowModal();
     }
 
diff --git a/src/slic3r/GUI/SSWCP.cpp b/src/slic3r/GUI/SSWCP.cpp
index d459f4504c..075fe3a0b3 100644
--- a/src/slic3r/GUI/SSWCP.cpp
+++ b/src/slic3r/GUI/SSWCP.cpp
@@ -4386,26 +4386,40 @@ void SSWCP_UserLogin_Instance::sw_DownloadFileAndOpen()
         std::string fileUrl  = m_param_data.count("file_url") ? m_param_data["file_url"].get<std::string>() : "";
 
         if (fileUrl.empty() || fileName.empty()) {
-            handle_general_fail(-1, "file_url and file_name are required");
+            handle_general_fail(-1, wxString::FromUTF8("file_url and file_name are required"));
             return;
         }
 
         // Use Download Manager
         DownloadManager* download_mgr = wxGetApp().download_manager();
         if (!download_mgr) {
-            handle_general_fail(-1, "Download Manager not available");
+            handle_general_fail(-1, wxString::FromUTF8("Download Manager not available"));
             return;
         }
 
-        wxGetApp().mainframe->downloadOpenProject(fileUrl, fileName, "");
+        // WebView script message runs inside the webview event handler; calling ShowModal() synchronously
+        // (via GenericDownloadDialog in downloadOpenProject) causes re-entrancy / crashes on Windows.
+        // Defer to the next event-loop iteration — same pattern as sw_UserLogin().
+        std::shared_ptr<SSWCP_UserLogin_Instance> self =
+            std::static_pointer_cast<SSWCP_UserLogin_Instance>(shared_from_this());
+        wxGetApp().CallAfter([self, fileUrl, fileName]() {
+            if (!wxGetApp().mainframe) {
+                self->handle_general_fail(-1, wxString::FromUTF8("Main window not available"));
+                return;
+            }
+            try {
+                wxGetApp().mainframe->downloadOpenProject(fileUrl, fileName, "");
+                self->m_status = 0;
+                self->m_msg    = "success";
+                self->send_to_js();
+                self->finish_job();
+            } catch (const std::exception& e) {
+                self->handle_general_fail(-1, wxString::FromUTF8(e.what()));
+            }
+        });
 
-        m_status = 0;
-        m_msg    = "success";
-        send_to_js();
-        finish_job();
-
-    } catch (std::exception& e) {
-        handle_general_fail(-1, e.what());
+    } catch (const std::exception& e) {
+        handle_general_fail(-1, wxString::FromUTF8(e.what()));
     }
 }