CF6 form with just over 100 checkboxes (for a survey) now generates an HTML error 500 message when I try to edit

Question

The setup is fairly basic ... writing a header record in one table and each response in another. Using partitions.

Has anyone else experienced this and, more importantly, found a fix, or is there a limit to how many fields one form can have?

Thanks!

farscape · Accepted Answer

OK, I got it working! Based on input from the site host, healyhatman, my ISP and Bob at Chronoengine, I made the following changes, in this order, and tested each before trying the next:

increased memory_limit in php.ini (suggested by the site's host)
switched from fast CGI to CGI (suggested by the site's host)
turned off mod_security (Suggested above by healyhatman. I've since turned that back on)
increased max_input_vars in php.ini (suggested by Bob, who said "a form with 100 checkboxes could have several thousand inputs in the admin form.")
increased max_execution_time in php.ini (Bob also suggested turning on Joomla error reporting, which revealed a timeout error. That last item in the list did the trick, although the other things might have contributed.)

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CF6 form with just over 100 checkboxes (for a survey) now generates an HTML error 500 message when I try to edit