Copy failure

API 27
AVD Pixel 2

Copy 5MB file.

Logcat:

07-31 13:02:50.841 com.amaze.filemanager W/System.err: java.lang.NullPointerException: Attempt to invoke virtual method 'android.net.Uri android.support.v4.provider.DocumentFile.getUri()' on a null object reference
        at com.amaze.filemanager.utils.files.GenericCopyUtil.startCopy(GenericCopyUtil.java:256)
07-31 13:02:50.842 com.amaze.filemanager W/System.err:     at com.amaze.filemanager.utils.files.GenericCopyUtil.copy(GenericCopyUtil.java:320)
        at com.amaze.filemanager.asynchronous.services.CopyService$DoInBackground$Copy.copyFiles(CopyService.java:486)
        at com.amaze.filemanager.asynchronous.services.CopyService$DoInBackground$Copy.execute(CopyService.java:387)
        at com.amaze.filemanager.asynchronous.services.CopyService$DoInBackground.doInBackground(CopyService.java:260)
        at com.amaze.filemanager.asynchronous.services.CopyService$DoInBackground.doInBackground(CopyService.java:224)
        at android.os.AsyncTask$2.call(AsyncTask.java:333)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
        at java.lang.Thread.run(Thread.java:764)
07-31 13:02:59.356 com.amaze.filemanager E/CopyService: Got exception checkout: /storage/emulated/0/Download/a.tar