What can I check or what could the problem be. When I go to issue an invoice I get this:
This page isn’t working xxxxxxxx.org is currently unable to handle this request.
HTTP ERROR 500
Don’t think this is related to Gibbon. Does this always happen or once a while? Can you paste the url?
We have been able to issue invoices for a full school term. But this started happening this (new) term. Here’s the url:
Are there any logs we can pull for that moment in time?
The two apache log files may help you: error.log and access.log.
Also check ownership/permissions of file invoices_manage_issueProcess.php on the server.
Good luck! 
Hi Tieku, sometimes Chrome reports a 500 error when other browsers would show a blank page or a PHP error. Definitely check the logs as Roman mentioned, and I suspect you’ll find something in error.log. Let us know what you find! Thanks, Ross.
Hi Tieku, those log files were useful, and showed that the errors are being caused by server-side cache files not being writable. If you go to Admin > System Admin > Cache Manager (v21 and higher), it should check for a fix any such issues. If that does not work, you’ll need to manually check ownership and permissions of the server-side cache, which lives in /uploads. Let us know if this helps.
Thanks. If you let me know what the ownership and permissions should be I can probably check and fix.
Should it be “safe” to upgrade my v20 site to v21? (I’ll backup everything first).
Hi Tieku, yes, it is safe to upgrade to v21, and definitely good to hear you are backing up first!
In terms of ownership and permissions, there is no simply solution. However, I tend to make sure everything in my Gibbon install is owned by the web-server user (www-data on Ubuntu Linux for example) and that that user has rwx permissions (e.g. mod 7).
Cheers,
Ross
Looks like I might have fixed the problem with a web host setting/tool which applies their default permissions to all the files in an application and changes ownership of all these files to that of the master user.