I think I've found a bug in MT 4.34. I recently moved hosts, and after setting up the run-periodic-tasks in my crontab, I see these errors in my MT activity log:
Error rebuilding file /home/[redacted]/public_html/help/copyright.html : Template 'Copyright Statement (Backup from 2008-06-08 15:10:37)' does not have an Output File.
They all correspond to backup templates. The output path is wrong since I have recently changed to a new host which uses a different file structure. I have deleted most of the backups but there are a few that I want to keep for a little while longer.
Is this a bug, or do I need to fix my configuration somehow?
Reported on Movable Type 4.3

Neil, that is supposed to be a legitimate error, when a template doesn't have an output file.
I would recommend you to set the backup templates to not rebuild and to make sure that you have a good path for all the other ones.
Thanks Mihai, but how do I set backup templates to not rebuild? MT does not expose the UI to do this to the user. The only option that can be changed for backup templates is the option to link it to a file. I'm sure it could be changed in the database but I wouldn't know where to start.
Also, I'm seeing these errors in my cron reports:
Use of uninitialized value in join or string at (eval 2215) line 2.
Use of uninitialized value in join or string at (eval 2218) line 2.
Use of uninitialized value in join or string at (eval 2221) line 2.
FWIW, I've seen RPT try to publish template backups, too. I've briefly looked into it a few times but haven't found an obvious answer. I mean, it must be a bug, but I don't understand any more of it than that!
What I would advise you is check the database for any traces of the previous hosting server path and replace that with the new server path everywhere it occurs.
That might automatically solve your problem!
Coming back to your issue, the error message you're getting should occur only in the following circumstances (all at once):
1) it is an index template;
2) it is set to static (which means to rebuild).
So I assume the template 'Copyright Statement (Backup from 2008-06-08 15:10:37' is not a backup template (meaning is not reached by clicking on 'Template Backups' from the templates section sidebar, under 'Useful links'), but an Index template.
Anyway, fix the paths first!
Thanks. The templates were definitely backups - removing them from the 'Template Backups' section stopped the errors from appearing.
You're welcome Neil!
The fact that movable type took into consideration 'template backups' means that indeed this is a bug.
I'm going to report this to the Six Apart crew!
That issue was happening only when running that script, or also on a movable type rebuild process?