After you update Windows to version 10.0.17134, a backup that includes OneDrive folder fails with an error similar to the following:
(error might be different if version 11 archive format is used)
Error code: 12
Message: The file is read-only.
Since this Windows update, OneDrive started storing actual data in the cloud. The files that you see in the OneDrive folder are "links" to the data in OneDrive cloud. As a result, it is not possible to back up these files.
Starting with version 7.7 update 1, OneDrive folder is excluded from backup. The backup plan completes successfully.
Backup of OneDrive with C2C Agent is implemented in Acronis Backup Cloud 7.8. Please update to the latest build once this version becomes available in your region.