During the run of archive.sh by crontab, it fail with a heavy backtrace (see attached file).
The first error is:
Warning: explode(): Empty delimiter. in /var/www/piwik/plugins/Actions/Actions.php on line 237
Keywords: archive actions
Attachment: Backtrace log of the error in Piwik archive.sh
Fixed in changeset  please apply the patch and that should fix the problem.
I confirm that the patch fix the problem. Thank you for your work :)