--- a/toolkit/components/printingui/nsPrintProgress.cpp
+++ b/toolkit/components/printingui/nsPrintProgress.cpp
@@ -72,17 +72,18 @@ NS_IMETHODIMP nsPrintProgress::OpenProgr
 
     array->AppendElement(ifptr);
 
     array->AppendElement(parameters);
 
     // We will set the opener of the dialog to be the nsIDOMWindow for the
     // browser XUL window itself, as opposed to the content. That way, the
     // progress window has access to the opener.
-    auto* pParentWindow = nsPIDOMWindowOuter::From(parent);
+    nsCOMPtr<nsPIDOMWindowOuter> pParentWindow = nsPIDOMWindowOuter::From(parent);
+    NS_ENSURE_STATE(pParentWindow);
     nsCOMPtr<nsIDocShell> docShell = pParentWindow->GetDocShell();
     NS_ENSURE_STATE(docShell);
 
     nsCOMPtr<nsIDocShellTreeOwner> owner;
     docShell->GetTreeOwner(getter_AddRefs(owner));
 
     nsCOMPtr<nsIXULWindow> ownerXULWindow = do_GetInterface(owner);
     nsCOMPtr<mozIDOMWindowProxy> ownerWindow = do_GetInterface(ownerXULWindow);

--- a/toolkit/components/printingui/nsPrintingPromptService.cpp
+++ b/toolkit/components/printingui/nsPrintingPromptService.cpp
@@ -64,16 +64,21 @@ nsPrintingPromptService::ShowProgress(
   nsIPrintProgressParams** printProgressParams,
   bool* notifyOnOpen)
 {
   NS_ENSURE_ARG(webProgressListener);
   NS_ENSURE_ARG(printProgressParams);
   NS_ENSURE_ARG(notifyOnOpen);
 
   *notifyOnOpen = false;
+  if (mPrintProgress) {
+    *webProgressListener = nullptr;
+    *printProgressParams = nullptr;
+    return NS_ERROR_FAILURE;
+  }
 
   nsPrintProgress* prtProgress = new nsPrintProgress(printSettings);
   mPrintProgress = prtProgress;
   mWebProgressListener = prtProgress;
 
   nsCOMPtr<nsIPrintProgressParams> prtProgressParams =
     new nsPrintProgressParams();