Not receiving IPNs from Paypal Standard

[minbori]

Figured I'd add to this post rather than start a new one because I'm having the exact same problem. All IPNs being sent from PayPal to CiviCRM are failing with error status 406.

At Lobo's suggestion I wrote a little script where I submitted the exact URL and message parameters that PayPal was using via CURL -- and that works!  Success messages in CiviCRM log, receipt emails sent successfully.

IPN data submitted via curl shows correctly as return code 200 in the Apache log.  PayPal's IPN POSTS show as return code 406 in the Apache logs.  And there are no errors in the CiviCRM logs regarding the PayPal IPNs, which makes me think those requests are never making it past Apache to CiviCRM. But why? My CURL Posts have no trouble.

Any thoughts?

[bighudsonnut]

I thought I would throw add this to the solutions.   When I started this thread I was on a Hostgator shared server.  My IPNs started working without me doing anything several months ago.  Just recently I moved over from the shared server (where IPNs were working) to a VPS server (dedicated) and lost my Paypal Standard IPN capability.  I worked for about a week with Hostgator support.  Finally today they fixed it and here was their response. 

"We have detected what appears to be the reason for PayPal IPNs from failing. It appears these requests were hitting a couple of mod_security rules in your VPS which was causing them to be blocked. We have gone ahead and Whitelisted these rules."

I asked for details so I could share I received the following reply 

"We cannot unfortunately provide many details about these rules as these are not part of the regular ruleset from mod_security but are internally developed ruleset. With that said we already notified our internal development team in charge of our internal rules. Our custom ruleset will be updated so that these rules are not triggered for this type of requests." 

One other thing I did was ensure that my server, CiviCRM, Paypal timezones were all on Central time.  I noticed even after I changed them all that my error logs sometimes showed UTC and other times America/Chicago.  Hostgator support fixed that as well however I cannot be sure that was part of the problem.

Hostgator support is excellent and has been very helpful, although sometimes it takes a while to find someone who knows enough and takes the time to dig into a problem.  The benefit for me was that the IPNs were working and the migration to the new server/service all within Hostgator broke them.  Hopefully this helps another Hostgator customer with the same issues.

Aaron

[bighudsonnut]

I will add one note to this thread.  A friend of mine who is on here as well had been having the same issues for months, used my solution and went to his provided and asked them to check their rules.  His IPNs are now working.  Looks like it is not only Hostgator that uses rule sets that may limit your ability to receive IPNs.

[Eileen]

I'm a big advocate of CiviHosting or other CiviCRM specific hosting for this sort of reason - hosting issues are just a headache you don't want to have