# What is never touched

Most migration anxiety is about deletion. Capable's migration only ever creates: new page versions, new diagram content, new asset copies. It reads originals and leaves them where they are.

That is a deliberate design choice, and it is what makes a migration something you can try on a real space rather than only in a sandbox.

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## The guarantees

* Nothing is deleted. Original attachments, preview images and vendor custom content are read but left in place; only new content is created.
* Every page a migration changes gets a new version labelled "Migrated by Capable", so the previous version, with the original vendor macro, stays in Confluence page history and can be restored.
* A page is only saved when its content actually changed, so a re-run over already-migrated pages creates no spurious versions.
* A macro that fails to convert is left exactly as it was on the page. A failure is never data loss, and a later run can convert it.
* Verification writes nothing at all, no page is saved and no content is created.
* Re-running is naturally incremental: once a page's macros are converted it no longer matches the search and drops out of scope, and already-migrated assets are recognised and reused rather than duplicated.
* Rollback restores by creating a new page version holding the old content, so the rollback itself is visible in history and can be undone.
* Every repair tool writes through a new page version with its own version message, so repairs are visible in page history too.

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## What that means in practice

| **If this happens**         | **What you still have**                                                      |
| --------------------------- | ---------------------------------------------------------------------------- |
| A macro fails to convert    | The original macro, untouched on the page                                    |
| A page converts badly       | The previous version in page history, with the original macro                |
| The whole run was a mistake | Every changed page's previous version, and a rollback tool driven by the log |
| You close the tab mid-run   | Everything written so far, plus every page not yet reached, unchanged        |

⚠️

**Rollback is not a full undo.** It restores page content. Assets the migration created are left in place, and the original vendor macros only render again while the vendor app is still installed. Do not uninstall the old app until you are satisfied.

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## A few things that catch people out

* Nothing here removes the need for a backup. It removes the need to panic.
* Keep source macros is the one option that leaves visible duplication behind, and it does not clean itself up.
* Uninstalling the source app is the point of no return, not the migration itself.

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## Related

[How a page is rewrittenWhere the new version comes from.](https://help.gocapable.com/migration/how-a-page-is-rewritten.html)

[Repair and rollbackUsing the safety net.](https://help.gocapable.com/migration/repair-and-rollback.html)

[Get startedTrying it safely.](https://help.gocapable.com/migration/get-started.html)

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_It only ever creates. Nothing is deleted._