IPN does not work anymore

[cluster]

WHMCS 7.4.3
PHP 7.0

since 2 days my paypal IPN does not work anymore ... I did not change anything

Billing Gateway Transaction Log is empty, nothing was stored during my test orders, just received payment notification from paypal

a few other entrys shows
Result > IPN Handshake Invalid

my Paypal IPN notify URL:
https://www.mydomain.tld/clients/

Paypal email notification:
Please check your server that handles PayPal Instant Payment Notifications (IPN). IPNs sent to the following URL(s) are failing:

https://www.mydomain.tld/clients/modules/gateways/callback/paypal.php

Paypal return URL is not activated yet, only IPN
should I activate the return url?

 

### edit ###

https://www.mydomain.tld/clients/modules/gateways/callback/paypal.php

shows:

HTTP ERROR 406

any idea?

 

Edited September 14, 2018 by cluster

[cluster]

some more details from apache log, seems to be ok

[14/Sep/2018:10:44:27 +0200] "POST /clients/viewinvoice.php?id=5938&paymentsuccess=true HTTP/1.1" 200 2530 "https://www.paypal.com/webapps/hermes?flow=1-P&ulReturn=true&country.x=LU&hermesLoginRedirect=xoon&locale.x=en_LU&mfid=1536914570856_1655fa243c80b&rm=2&token=xxxx&useraction=commit&country.x=LU&locale.x=en_US" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.92 Safari/537.36"

 

[cluster]

and now the gateway log shows:

IPN Handshake Invalid

and yes, paypal & whmcs ist set to utf-8 encoding

Edited September 14, 2018 by cluster

[cluster]

seems to be a bug or paypal changed something ...

I have also replaced viewinvoice.tpl with a new one, same result IPN Handshake invalid

[Kian]

Take a look here: IPN Handshake Invalid. Probably it's a problem with charset. Enable Module Debugging (Utilities > Log > Module Log) and see what you have in your Request. Look for weird chars.

[cluster]

strange ... after an PHP update (debian 9) it start working again!