We are seeing the following error when uploading new files to the libraries module...
ProviderException: Access to the path <<UploadDirectory>> is denied
The strange thing is that is very intermittent. Sometimes it works and sometimes it doesn't and often when it fails it will succeed with the very next attempt. This suggest to me that it is not a simple directory permissions problem.
We are using the Files streaming provider and have overridden the libraries provider and file system provider to set a custom upload directory.