Should be a defect, since it's not i18n.

<pre>
/var/redmine/app% grep -nr 'Unable to delete version' *
controllers/.svn/text-base/versions_controller.rb.svn-base:37: flash[:error] = "Unable to delete version"
controllers/versions_controller.rb:37: flash[:error] = "Unable to delete version"
</pre>

Only one occurence in the app: version_controller.rb:37.
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Jean-Philippe, can I apply this patch to versions_controller.rb?
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Yes, you can. Here is how to add the new string to every lang files: add it to en.yml after the existing notice strings (around line 80) and run rake gloc:update.
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Solved in r1829, thank to Antti Perkiömäki for reporting.
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