--- a/dom/system/IOUtils.cpp
+++ b/dom/system/IOUtils.cpp
@@ -273,37 +273,37 @@ already_AddRefed<Promise> IOUtils::Write
   opts.mNoOverwrite = aOptions.mNoOverwrite;
   if (aOptions.mBackupFile.WasPassed()) {
     opts.mBackupFile.emplace(aOptions.mBackupFile.Value());
   }
   if (aOptions.mTmpPath.WasPassed()) {
     opts.mTmpPath.emplace(aOptions.mTmpPath.Value());
   }
 
-  // return RunOnBackgroundThread<uint32_t>(promise, &WriteAtomicSync, destPath,
-  //                                       std::move(toWrite), std::move(opts));
+  return RunOnBackgroundThread<uint32_t>(promise, &WriteAtomicSync, destPath,
+                                         std::move(toWrite), std::move(opts));
 
-  InvokeAsync(bg, __func__,
+  /*InvokeAsync(bg, __func__,
               [destPath = nsString(aPath), toWrite = std::move(toWrite),
                opts = std::move(opts)]() {
                 MOZ_ASSERT(!NS_IsMainThread());
                 auto rv = WriteAtomicSync(destPath, toWrite, opts);
                 return ToMozPromise<IOWriteMozPromise, uint32_t, IOError>(
                     rv, __func__);
               })
       ->Then(
           GetCurrentSerialEventTarget(), __func__,
           [promise = RefPtr(promise)](const uint32_t& aBytesWritten) {
             promise->MaybeResolve(aBytesWritten);
           },
           [promise = RefPtr(promise)](const IOError& aError) {
             RejectJSPromise(promise, aError);
           });
 
-  return promise.forget();
+  return promise.forget();*/
 }
 
 /* static */
 already_AddRefed<Promise> IOUtils::Move(GlobalObject& aGlobal,
                                         const nsAString& aSourcePath,
                                         const nsAString& aDestPath,
                                         const MoveOptions& aOptions) {
   RefPtr<Promise> promise = CreateJSPromise(aGlobal);