# Issues reconfiguring backups after Windows -\> Linux OS migration

**URL:** <https://forum.duplicati.com/t/issues-reconfiguring-backups-after-windows-linux-os-migration/21457>\
**Category:** Support\
**Created:** [October 23, 2025, 4:56pm UTC](https://forum.duplicati.com/t/issues-reconfiguring-backups-after-windows-linux-os-migration/21457 "2025-10-23T16:56:38Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![ts678](https://forum.duplicati.com/letter_avatar_proxy/v4/letter/t/8491ac/32.png) [@ts678](https://forum.duplicati.com/u/ts678)\
**Post date:** [October 24, 2025, 11:22pm UTC](https://forum.duplicati.com/t/issues-reconfiguring-backups-after-windows-linux-os-migration/21457/2 "2025-10-24T23:22:53Z")

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Welcome to the forum @noodle

> [@noodle](#):
>
> I have also looked into setting up a new backup from scratch, using the same source. But I cannot do this because
> 
> `The remote destination already contains a backup. Please use a different folder for each backup.`

This path should be super simple, right? The question is whether it’s what you want to have.  
You can do cross-platform restore from your old backup if you have space to keep it around.

> [@noodle](#):
>
> According to the CLI docs I found, the flag ”Performs a compact process after purging files”, which does not seem to do what the name implies. In fact, it seems like the _opposite_ of what I am looking for. Any explanation here would be appreciated.

If you mean [CLI docs for `purge`](https://docs.duplicati.com/community-docs/community-docs-using-duplicati-from-the-commandline#the-purge-command), I think you found a [bug from 2016](https://github.com/duplicati/duplicati/commit/4bf4871427dc022afa469d6d959b79521d04a78e#diff-ec777293b4faa6f22ce421612128b8e2aeedfcf684134db6d579baf38e7a7382) on a secondary reference.  
Primary references are usually better, but sometimes built-in help is more current than [manual](https://docs.duplicati.com/community-docs/community-docs-advanced-options#no-auto-compact).

> `--no-auto-compact = false` If a large number of small files are detected during a backup, or wasted space is found after deleting backups, the remote data will be compacted. Use this option to disable such automatic compacting and only compact when running the compact command.

looks about right to me, or at least not backwards. The reason the suggestion is suggesting a

> `delete all filesets and make sure the --no-auto-compact option is set`

is if you don’t, data in the destination gets deleted because it suddenly became wasted space.  
What this plan is trying to do is to let you reuse your existing destination data in a new backup. Situations where the goal is to avoid big uploads might appreciate that. Others might not care.

You still wind up with current version. Converting history is harder (thus the awful procedures)  
because things like file permissions are different between OS, so are best obtained at backup.

[Change of Duplicati server (+ OS) without losing the remote data](https://forum.duplicati.com/t/change-of-duplicati-server-os-without-losing-the-remote-data/15826/3) was a 2023 dev explanation, question the wording. The raw data blocks are at destination for awhile, but old backups aren’t.

> [@noodle](#):
>
> Restoring works

proves that some level of conversion is possible, but further comment would need developer. Possibly it boils down to a question of priority. Things that are rarely asked might be deferred.

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