What is happening?

Spanning has taken a decision to end of life Google Backup for Classic sites. After March 31, 2024 Spanning Backup will no longer provide access to backups for Google Classic sites.

What you need to do?

If you still need data from backups you can export this data from Spanning servers before March 31, 2024 and store it offline.

Why is this happening now?

Google has deprecated classic sites and all customers should be already migrated to Google Modern sites a long time ago.

Source: https://support.google.com/a/answer/9958187?hl=en , https://support.google.com/sites/answer/10598263?hl=en&ref_topic=6372873

Can Spanning support Google Modern Sites backup?

No. Google didn't provide API for Modern sites backup.

https://issuetracker.google.com/issues/36761330