PayPal - IPN Handshake Invalid

    Hallo,


    seid kurzem zeigt mir PayPal den Fehler an:


    IPN Handshake Invalid


    Selbst mit einem IPN Test...
    Woran kann das liegen?


    Log:

    Code
    payment_type => instantpayment_date => Mon Jul 06 2015 20:12:31 GMT+0200 (CEST)payment_status => Pendingaddress_status => confirmedpayer_status => verifiedfirst_name => Johnlast_name => Smithpayer_email => buyer@paypalsandbox.compayer_id => TESTBUYERID01address_name => John Smithaddress_country => United Statesaddress_country_code => USaddress_zip => 95131address_state => CAaddress_city => San Joseaddress_street => 123 any streetbusiness => seller@paypalsandbox.comreceiver_email => seller@paypalsandbox.comreceiver_id => seller@paypalsandbox.comresidence_country => USitem_name => somethingitem_number => AK-1234quantity => 1shipping => 3.04tax => 2.02mc_currency => USDmc_fee => 0.44mc_gross => 12.34mc_gross1 => 12.34txn_type => web_accepttxn_id => 918712898notify_version => 2.1custom => xyz123invoice => abc1234test_ipn => 1verify_sign => AFcWxV21C7fd0v3bYYYRCpSSRl31AR7MP8PqN572BCOBAQNZvnvhviw6


    HTTP Fehlercode: 406

    Force One Time Payments Never show the subscription payment button
    Force Subscriptions Hide the one time payment button when a subscription can be created
    Require Shipping Address Tick this box to request a shipping address from a user on PayPal's site
    Client Address Matching Tick this box to force using client profile information entered into WHMCS at PayPal


    NIchts angeakt außer Force One Time Payments..