Error=“java.io.IOException: [ReadFile] (381) The cloud operation is not supported on a read-only volume” on OneDrive
This error is only seen when backing up a local OneDrive folder on a Windows device. It isn’t seen when backing up OneDrive data from the cloud using our cloud-to-cloud connector.
OneDrive has a feature named Files On Demand that creates symbolic links on a PC pointing to the folders and files on their cloud service. It doesn’t download the files until the user accesses them. This means our software detects what it believes to be a file, but is only a read-only link.
Disable Files On Demand within OneDrive. If there are only a few files with the error, these can be downloaded instead to the local drive by opening them.
Exclude the read-only local OneDrive files from the backup source.
Use our software to backup the OneDrive data directly from Microsoft’s cloud instead of from the device’s desktop. This is the recommended method because you will also be able to restore back to their cloud.
Our software comes with cloud-to-cloud connectors in the desktop and server versions. These allow you to backup the main cloud storage and drive services.
The cloud-to-cloud connectors are free to use.
This tech doc explains how to create a cloud-to-cloud backup: