Unable to Back up On-Demand Files (code 1634)

Situation

A backup plan failed with the following error message: Some On-Demand files cannot be backed up. These files are stored only online due to File On-Demand option enabled for them.

Cause

This error only affects file backups of OneDrive folders with the Files On-Demand option enabled. When Files On-Demand is enabled for your OneDrive folder, it saves disk space by not copying files to the computer; instead, new files created online or on another device appear as online-only files in File Explorer.

Solutions

Solution 1

Disable the Files On-Demand option. Note that this will increase the disk space usage on the affected client computer. Then start the backup plan again.

Solution 2

Exclude the affected On-Demand files from the backup dataset.