IPN not working

all of the sudden my IPN is not working from paypal so none of my subscriptions are working properly which is very upsetting as you can imagine.
the only change made was adding an ssl to the site. i have joomla set to force ssl on entire site.
is this causing the issue of the ipns not working? is there a setting that i need to fix? please advise so i can resolve the issue. thanks

after speaking with paypal i have found that it is an internal server error meaning that cbsubs is not sending the correct information back to paypal (500 error). as i know the ipn script has no issues, could this be due to the https that you helped add to my acct?
paypal said that it could possibly be because all the accounts that were created before adding the ssl would have http attached to it & that may be causing an issue with the return if the https is beging forced. i had both the joomla "entire site" forcing ssl & the cbsubs "force https on cbsubs forms". i have now changed the joomla to "none" and cbsubs to "keep http/https the same".
do you believe this could be the issue? i have never had this happen before.
thank you

If all the payment information, including the IPN URL, stored in PayPal points to HTTP and you are forcing all URLs to HTTPS then yes this could be causing an issue as it's basically a redirect and CBSubs needs the POST information, which is lost on a redirect. Check within your PayPal IPN History and see what the URL is then try and copy/paste to your browser address bar and see what happens when you navigate to it.

i did that, it was giving me INVALID
i have looked back at the history & tried to resend the ipn's from paypal & i believe the it fixed the issue. however it has now added an extra month to their subscriptions instead of ending 5/3/13 it set it to 6/3/13 because i had to manually resubscribe them when they emailed & could not access the site.
is there any way to fix this? is there anywhere to edit the actual subscription information?
in paypal the recurring payment appears to still be for 5/3/13 which is correct, but what happens next month when the payment goes thru? will it set it to 7/3/13?
it would be great if i could somehow edit the actual date.
thank you for the support! fingers crossed on this:)

As you manually fixed it then forced the IPN to resend you double renewed. You'll need to edit the subscription within CBSubs > Subscriptions by clicking the id of the subscription under the ID column and fix the dates.

thank you very much for the above information. i have successfully been able to change the dates.
however unfortunately i received another email from paypal at 1am today stating the same thing, the xxxxxx url's are failing.
is there any other reason this could be happening? nothing on the site has changed other than when we added the ssl! i recall you helping me with that so is there anything that you can imagine that could cause this?
i have checked the IPN history in paypal & see that all other payments to my other shopping cart are going thru no problem.
the ones that are not are attached to cbsubs. there were 3 urls sent today that failed & 4 yesterday. the ones from today are the same as yesterday & i believe are from the retrying of paypal ipn.
any thoughts?
thank you