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If the destination field is 'Fix Version/s', 'Affects Version/s' or some custom field of type 'Version Picker', you can choose that a new version will be created in the target project, if does not yet exist. If you don't choose this option and that version does not yet exist, the user will get an error message and the transition won't will complete.
However be aware, that a user needs the 'Administer Projects' permission to be able to create a new version.
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If the destination field is 'Components', you can choose that a new component will be created in the target project, if does not yet exist. If you don't choose this option and that component does not yet exist, the user will get an error message and the transition won't will complete.
However be aware, that a user needs the 'Administer Projects' permission to be able to create a new component.
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