filepath = "test.file" # about 300Mb
r = client.files_upload(file=open(filepath, "rb"), channels="MYCHANNELID")
print(r.data)

error:
slack_sdk.errors.SlackApiError: The request to the Slack API failed. (url: https://www.slack.com/api/files.upload)
The server responded with: {'ok': False, 'error': 'error_creating_file_sync'}

what means "error_creating_file_sync" ?????