error in bot after Added to queue... command received

[branchmaster]

Hi Adnan ,
I'm get an error below after Added to queue... command received in bot :
" expected str, bytes or os.PathLike object, not NoneType "
I'll try to set env var value for DOWNLOAD_DIR is empty & / but in both received eror too.
my application log for allprocess write below :

2021-04-23T07:40:57.420214+00:00 app[worker.1]: Traceback (most recent call last): 2021-04-23T07:40:57.420215+00:00 app[worker.1]: File "/app/.heroku/python/lib/python3.9/site-packages/pyrogram/client.py", line 509, in handle_download 2021-04-23T07:40:57.420215+00:00 app[worker.1]: shutil.move(temp_file_path, final_file_path) 2021-04-23T07:40:57.420216+00:00 app[worker.1]: File "/app/.heroku/python/lib/python3.9/shutil.py", line 826, in move 2021-04-23T07:40:57.420216+00:00 app[worker.1]: copy_function(src, real_dst) 2021-04-23T07:40:57.420216+00:00 app[worker.1]: File "/app/.heroku/python/lib/python3.9/shutil.py", line 435, in copy2 2021-04-23T07:40:57.420217+00:00 app[worker.1]: copyfile(src, dst, follow_symlinks=follow_symlinks) 2021-04-23T07:40:57.420217+00:00 app[worker.1]: File "/app/.heroku/python/lib/python3.9/shutil.py", line 264, in copyfile 2021-04-23T07:40:57.420217+00:00 app[worker.1]: with open(src, 'rb') as fsrc, open(dst, 'wb') as fdst: 2021-04-23T07:40:57.420218+00:00 app[worker.1]: OSError: [Errno 30] Read-only file system: '/video_2021-04-22_09-09-31_6954254937751912448.mp4'

waiting for your response
finest regards

[zYxDevs]

change value of var DOWNLOAD_DIR to downloads/