** 500 Internal Error Message... Any suggestions on how to get things up and running again. **
A 500 server error just means something has gone wrong, it says nothing about what. Either check the server logs to see if a more detailed error message was recorded or if you have shell access (telnet, SSH, etc.), try running the script from there to see what error(s) Perl reports.
Once you get more details, if you post them here we'll see if we can suggest something. My guess is that if you didn't change anything your self, possibly some file or directory permissions have changed, maybe from a server upgrade.
** if i upgrade to 3.21 do i need to pay my $ again. **
If you've registered a previous 3+ CalendarScript version and you're only running it on one server under a single domain name, you do not need to pay a second time.
JMO
Dan O.
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