# Large backup fails after first successful run **URL:** https://forum.duplicati.com/t/large-backup-fails-after-first-successful-run/9250 **Category:** Support **Created:** [February 20, 2020, 5:09pm UTC](https://forum.duplicati.com/t/large-backup-fails-after-first-successful-run/9250 "2020-02-20T17:09:12Z") **Posts on this page:** 1 **Showing post:** 15
### Author: ![ts678](https://forum.duplicati.com/letter_avatar_proxy/v4/letter/t/8491ac/32.png) [@ts678](https://forum.duplicati.com/u/ts678) #### Post date: [February 21, 2020, 6:20pm UTC](https://forum.duplicati.com/t/large-backup-fails-after-first-successful-run/9250/15 "2020-02-21T18:20:00Z")
A synthetic filelist tries to give you a synthetic backup version that’s the past one plus whatever made it before interruption of next backup, but that’s arguably unessential if next good backup is close enough. [Warning Message after Backup](https://forum.duplicati.com/t/warning-message-after-backup/965/7) is my explanation for why message expects a dblock instead of a dlist, which is what represents files in a version. It’s a bad lookup. I’d like a great test case, but don’t have it. [Warning: Expected there to be a temporary fileset for synthetic filelist #2329](https://github.com/duplicati/duplicati/issues/2329#issuecomment-449896156) is closed. Need new issue. Back to the primary issue, this is adding fuel to the theory that this particular unfortunate ending (which is arguably a bug in itself), is a follow-on error to some other issue. Maybe we also need a test case for this. Sometimes details obscure overall picture, e.g. visible using About --\> Show log --\> Live --\> Retry which would probably have shown [–number-of-retries](https://duplicati.readthedocs.io/en/latest/06-advanced-options/#number-of-retries) retries before giving up then taking error paths… --- _[View the full topic](https://forum.duplicati.com/t/large-backup-fails-after-first-successful-run/9250)._