diff --git a/dom/clients/manager/ClientManagerService.cpp b/dom/clients/manager/ClientManagerService.cpp
index 76ecb97a367d..afbd86116996 100644
--- a/dom/clients/manager/ClientManagerService.cpp
+++ b/dom/clients/manager/ClientManagerService.cpp
@@ -601,6 +601,14 @@ public:
                                                   nullptr);
     }
 
+    // But starting a process can failure for any number of reasons. Reject the
+    // promise if we could not.
+    if (!targetProcess) {
+      mPromise->Reject(NS_ERROR_ABORT, __func__);
+      mPromise = nullptr;
+      return NS_OK;
+    }
+
     ClientOpenWindowOpParent* actor =
       new ClientOpenWindowOpParent(mArgs, mPromise);
 
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index 74d09b99814c..d717e549b5f8 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -1989,6 +1989,11 @@ ContentParent::LaunchSubprocess(ProcessPriority aInitialPriority /* = PROCESS_PR
 {
   AUTO_PROFILER_LABEL("ContentParent::LaunchSubprocess", OTHER);
 
+  if (!ContentProcessManager::GetSingleton()) {
+    // Shutdown has begun, we shouldn't spawn any more child processes.
+    return false;
+  }
+
   std::vector<std::string> extraArgs;
   extraArgs.push_back("-childID");
   char idStr[21];