I've had issues with paypal IPN notification warnings on this site in the past. I understand that there's no reason for IPN and DT Register to just "stop working"...but the fact remains that intermittently, paypal IPN just fails for a number of records in a row.
I've checked all the settings, and IPN is enabled and pointed to the correct URL in Paypal, and auto-return is OFF.
Permissions for the site are at 755 for all directories, and 644 for files.
But with none of that changing, running Joomla 1.5.26 and DT Register 2.7.18a, this still just seems to happen, and I can't find any reason for it, nor any way to fix it.
Any suggestions for what to check that I haven't checked? I saw posts from a couple of people that the problem was with group registrations, but I'm not sure what to look at there, to see if that is where the problem lies.
You should update to 2.7.19 as a starting point. However, there are no PayPal issues with DT Register. If you have the latest version and occasional problems, that means there is SOMETHING causing IPN to not be able to communicate with your site. The times when it works is when the user manually clicks to return to your site... and IPN is not needed to complete it.
If everything you stated is really okay, then remaining causes could be a restriction coming from your .htaccess file or a firewall setup. Something is blocking your IPN... you just have to sort out what it is.
I had mentioned seeing instances of people posting problems with IPN on group registrations. It is beginning to look like that may be where the issue lies.
Is there something specific in the setup that I need to do for group registrations that would cause that sort of issue? I notice that you didn't address that issue at all, even though I asked about it.
I'm not saying that there is a problem with DT Register and Paypal, I am attempting to find a solution to the issue that this site seems to be having. Any other suggestions would be welcome.
PayPal doesn't care if your registration is an individual or a group. If your issues seem to be tied to group registrations, then it's probably not a PayPal problem at all, but a setup issue with your event. Try using a pay option like Pay Later and see if your group record is created. That's an easy way to tell if the issue is even connected to PayPal in the first place.
For a group record to be created, you MUST have at least the fields firstname, lastname and email included for group BILLING. If you have not set this up correctly and bypassed those fields for group billing, then your group record will NOT be created... regardless of payment.