My site was recently moved to a new server and I noticed that my Action Stream in Movable Type was old / not updated.
I spent a long time trying to track down why it wasn't working. Eventually I decided to set cron to email me when it executed my one recurring cron job. This yielded emails that said:
/bin/sh: line 0: cd: /public_html/blog/: No such file or directory
Can't open perl script "./tools/run-periodic-tasks": No such file or directory
That's straightforward enough. I figured that when my site got moved, something in the directory path changed.
So I checked Cpanel and found my new home directory name. I changed the cron job to reflect the new path.
I got a big error-filled email after that. So, it seems I have at least gotten cron pointed to the right place. Here is a shortened version of the email:
Use of uninitialized value in join or string at (eval 185) line 2.
Use of uninitialized value in join or string at (eval 187) line 2.
Use of uninitialized value in join or string at (eval 189) line 2.
Use of uninitialized value in join or string at (eval 191) line 2.
Use of uninitialized value in join or string at (eval 193) line 2.
Use of uninitialized value in join or string at (eval 195) line 2.
Use of uninitialized value in join or string at (eval 197) line 2.
Use of uninitialized value in string eq at /(path to MT)/plugins/Textile/lib/Text/Textile.pm line 1557.
Use of uninitialized value in string eq at /(path to MT)/plugins/Textile/lib/Text/Textile.pm line 1558.
Use of uninitialized value in string eq at /(path to MT)/plugins/Textile/lib/Text/Textile.pm line 1557.
Use of uninitialized value in string eq at /(path to MT)/plugins/Textile/lib/Text/Textile.pm line 1558.
(i edited out my exact directory. also, the email repeats these final two lines for about a full page)
At this point I am totally out of my depth. I really need some help. Can anyone tell me what is wrong?
Reported on Movable Type 5

Those are not errors, they're warnings (warnings are just very strong suggestions that you shouldn't do something in Perl). Your copy of Action Streams should have the ability to do a manual update. Open up your user profile, go to the action streams part and see if you can manually update it. If not, then the problem is not with Cron, but likely with Action Streams.