Cause

The following error is displayed when a backup fails for SharePoint sites deleted from Microsoft 365:

[ERROR] SharePoint Backup failed for sitecollection: 5911869, reason: Requested site collection does not exist. (#10000010e)

Resolution

To resolve this issue, disable backup from inSync for SharePoint sites that are deleted from Microsoft 365.

To disable backup for SharePoint  sites from insync, perform the following steps:

1. On the inSync Management Console menu bar, click Data Sources > Microsoft 365. An overview page that provides a holistic view of all the configured Microsoft 365 app appears.
2. On the left-hand panel, click SharePoint. A page that lists all the discovered sites appears.
3. Select the site title that you want to disable. Click the    icon and click Disable. A confirmation dialog box appears. Click Disable.