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If you need to change the target space after content has already been published from the source space , only content that has not been previously published can be published to the new space.The space settings Publishing configuration dashboard on selecting a new target space the dashboard will display a warning banner.
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To publish all the content in the source space to a new target space you can either
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delete the previous target space (or delete the previously published documents from this previous target space)
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The warning message will be displayed before selection of the Change button.
Confirming the Change of target space
unlinks the current target space and published pages in this old target space will be no longer linked for publishing
sets all pages in the source space as unpublished and the publishing status to NEW
Source source pages will need to be published to the new target space
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If you don't delete the previous .
Previous target space
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published documents are not deleted and are no longer updated.
For spaces with a large number of pages, publishing should not be attempted whilst the change of target space is in progress.