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HTML Code:
<p>IPN ERROR :: No saved Website Payments Standard session data available. Must be an Express Checkout or Direct Pay transaction.
Could be a test notification, or the incoming IPN notification is not actually a bonafide PayPal transaction.
NOTE: It is likely that all the following log content is meaningless or irrelevant.</p>
I'm trying to find out if these are legit transactions or some kind of test they are doing to make fraudulent purchases, or an error in the plugin ...

HTML Code:
<p>IPN FATAL ERROR :: No POST data available -- Most likely initiated by browser and not PayPal.


     *** The rest of this log report can most likely be ignored !! ***</p><p>
IPN ERROR :: Could not find stored session {} in DB; thus cannot validate or re-create session as a transaction awaiting PayPal Website Payments Standard confirmation initiated by this store. Might be an Express Checkout or eBay transaction or some other action that triggers PayPal IPN notifications.</p><p>
IPN ERROR :: No saved Website Payments Standard session data available. Must be an Express Checkout or Direct Pay transaction.
Could be a test notification, or the incoming IPN notification is not actually a bonafide PayPal transaction.
NOTE: It is likely that all the following log content is meaningless or irrelevant.</p><p>IPN ERROR :: Could not find stored session {} in DB; thus cannot validate or re-create session as a transaction awaiting PayPal Website Payments Standard confirmation initiated by this store. Might be an Express Checkout or eBay transaction or some other action that triggers PayPal IPN notifications.</p>
<p>IPN FATAL ERROR :: No POST data available -- Most likely initiated by browser and not PayPal.


     *** The rest of this log report can most likely be ignored !! ***
</p>

<p>IPN PROCESSING INITIATED. 
*** Originating IP: 176.9.54.197  yadla.de
*** Browser/User Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)</p>
<p>IPN INFO - POST VARS received (sorted):
Array
(
)

</p>
<p>Breakpoint: Flag Status:
isECtransaction = 0
isDPtransaction = 0
</p>
<p>Breakpoint: 0 - Initializing debugging.
</p><p>IPN PROCESSING INITIATED. 
*** Originating IP: 176.9.54.197  yadla.de
*** Browser/User Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)


</p>
<p>IPN INFO - POST VARS received (sorted):
Array
(
)


</p><p>Breakpoint: Flag Status:
isECtransaction = 0
isDPtransaction = 0

</p><p>Breakpoint: 0 - Initializing debugging.
</p><p>IPN ERROR :: No saved Website Payments Standard session data available. Must be an Express Checkout or Direct Pay transaction.
Could be a test notification, or the incoming IPN notification is not actually a bonafide PayPal transaction.
NOTE: It is likely that all the following log content is meaningless or irrelevant.

</p><p>IPN ERROR :: Could not find stored session {} in DB; thus cannot validate or re-create session as a transaction awaiting PayPal Website Payments Standard confirmation initiated by this store. Might be an Express Checkout or eBay transaction or some other action that triggers PayPal IPN notifications.</p><p>IPN FATAL ERROR :: No POST data available -- Most likely initiated by browser and not PayPal.


     *** The rest of this log report can most likely be ignored !! ***
</p><p>paypalwpp
Checking to see if we are in markflow
cart contents: physical

NOTE: $this->showPaymentPage = 0
Customer ID: 0
Session Data: Array
(
    [securityToken] => d9f379ba89a3d605d4f925bb031e43b8
    [customers_host_address] => host-217-131-196-92.reverse.superonline.net
    [cartID] => 
    [cart] => shoppingCart Object
        (
            [contents] => Array
                (
                    [678ad11] => Array
                        (
                            [qty] => 2
                        )

                    [678ad12] => Array
                        (
                            [qty] => 2
                        )

                    [678] => Array
                        (
                            [qty] => 1
                        )

                )

            [total] => 415.9
            [weight] => 0
            [cartID] => 91624
            [content_type] => physical
            [free_shipping_item] => 5
            [free_shipping_weight] => 0
            [free_shipping_price] => 415.9
            [download_count] => 0
            [total_before_discounts] => 415.905
            [display_debug_messages] => 
            [flag_duplicate_msgs_set] => 
        )

    [check_valid] => true
    [language] => english
    [languages_id] => 1
    [languages_code] => en
    [currency] => USD
    [today_is] => 2019-02-13
    [updateExpirations] => 1
    [category_tree] => SimpleCategoriesTree Object
        (
            [category_tree] => Array
                (
                    [1] => Array
                        (
                            [name] => Women's Perfumes
                            [parent_id] => 0
                            [path] => Array
                                (
                                    [0] => 1
                                )

                            [sub] => no_sub
                            [cPath] => 1
                            [nPath] => 1
                        )

                    [0] => Array
                        (
                            [sub_cats] => Array
                                (
                                    [0] => 1
                                    [1] => 2
                                )

                            [sub] => has_sub
                            [cPath] => 0
                            [nPath] => 0
                        )

                    [2] => Array
                        (
                            [name] => Men's Fragrances
                            [parent_id] => 0
                            [path] => Array
                                (
                                    [0] => 2
                                )

                            [sub] => no_sub
                            [cPath] => 2
                            [nPath] => 2
                        )

                )

            [is_deepest_cats_built] => 
            [parent_html] => 
            [child_html] => 
            [current_id] => -1
            [exceptional_list] => Array
                (
                )

            [new_id] => 
            [is_attached] => 
        )

    [session_counter] => 1
    [customers_ip_address] => 217.131.196.92
    [new_products_id_in_cart] => 678
    [valid_to_checkout] => 1
    [cart_errors] => 
    [payment] => paypalwpp
    [shipping_overide] => 1
    [cot_gv] => 0
)

</p><p>paypalwpp
address details from override check: <NONE FOUND></p><p>paypalwpp
cart content is not all virtual (or customer is not logged in) ... therefore will be submitting address details

</p><p>paypalwpp
not logged in and not in markflow mode - nothing to override</p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p>paypalwpp
Array
(
    [AMT] => 415.91
    [ITEMAMT] => 415.91
    [L_NAME0] => All the items in your shopping basket (see details in the store and on your store receipt).
    [L_AMT0] => 415.91
    [CURRENCYCODE] => USD
    [LOCALECODE] => US
    [GIFTMESSAGEENABLE] => 0
    [GIFTRECEIPTEENABLE] => 0
    [GIFTWRAPENABLE] => 0
    [GIFTWRAPNAME] => 
    [GIFTWRAPAMOUNT] => 0
    [BUYEREMAILOPTINENABLE] => 0
    [CUSTOMERSERVICENUMBER] => 
    [BRANDNAME] => Outlet Season Scentia
    [PAYMENTACTION] => Sale
    [ALLOWNOTE] => 1
    [SOLUTIONTYPE] => Sole
    [LANDINGPAGE] => Billing
    [NOSHIPPING] => 0
    [RETURNURL] => https://www.theoutletseason.com/scentia/ipn_main_handler.php?type=ec&zenid=ajak84gdhrp2hmcevsgpg8aso6
    [CANCELURL] => https://www.theoutletseason.com/scentia/shopping_cart.html?ec_cancel=1&zenid=ajak84gdhrp2hmcevsgpg8aso6
)
</p><p>paypalwpp
subtotals balance - okay
</p><p>paypalwpp
Line-item subtotals do not add up properly. Line-item-details skipped.
415.9 415.9 Array
(
    [AMT] => 415.91
    [ITEMAMT] => 415.91
    [TAXAMT] => 0
    [SHIPPINGAMT] => 0
    [SHIPDISCAMT] => 0
    [HANDLINGAMT] => 0
    [INSURANCEAMT] => 0
    [L_NUMBER0] => 414371
    [L_NAME0] => JEAN PAUL GAULTIER by Jean Paul Gaultier for Women Eau De Parfum Spray 3.3 oz [678]
    [L_QTY0] => 2
    [L_AMT0] => 83.18
    [L_NUMBER1] => 414371
    [L_NAME1] => JEAN PAUL GAULTIER by Jean Paul Gaultier for Women Eau De Parfum Spray 3.3 oz [678]
    [L_QTY1] => 2
    [L_AMT1] => 83.18
    [L_NUMBER2] => 414371
    [L_NAME2] => JEAN PAUL GAULTIER by Jean Paul Gaultier for Women Eau De Parfum Spray 3.3 oz [678]
    [L_QTY2] => 1
    [L_AMT2] => 83.18
)

</p><p>paypalwpp
checking subtotals... 
Array
(
    [calculated total] => 415.91
    [AMT] => 415.91
    [ITEMAMT] => 415.91
)

-------------------
difference: 0  (abs rounded: 0)


</p><p>paypalwpp
BEFORE line-item calcs: Array
(
    [AMT] => 415.91
    [ITEMAMT] => 415.91
    [TAXAMT] => 0
    [SHIPPINGAMT] => 0
    [SHIPDISCAMT] => 0
    [HANDLINGAMT] => 0
    [INSURANCEAMT] => 0
)
AFTER doing line-item calcs: Array
(
    [AMT] => 415.91
    [ITEMAMT] => 415.91
    [TAXAMT] => 0
    [SHIPPINGAMT] => 0
    [SHIPDISCAMT] => 0
    [HANDLINGAMT] => 0
    [INSURANCEAMT] => 0
    [L_NAME0] => All the items in your shopping basket (see details in the store and on your store receipt).
    [L_AMT0] => 415.91
)</p><p>2019-02-13 12:07:34
-------------------
(live transaction) --> https://api-3t.paypal.com/nvp
Request Headers: 
Array
(
    [0] => Content-Type: text/namevalue
    [1] => X-VPS-Timeout: 90
    [2] => X-VPS-VIT-Client-Type: PHP/cURL
    [3] => X-VPS-VIT-Integration-Product: PHP::Zen Cart(R) - PayPal/NVP
    [4] => X-VPS-VIT-Integration-Version: 1.5.3
)


Request Parameters: {SetExpressCheckout} 
Array
(
    [AMT] => 415.91
    [ITEMAMT] => 415.91
    [L_NAME0] => All the items in your shopping basket (see details in the store and on your store receipt).
    [L_AMT0] => 415.91
    [CURRENCYCODE] => USD
    [LOCALECODE] => US
    [GIFTMESSAGEENABLE] => 0
    [GIFTRECEIPTEENABLE] => 0
    [GIFTWRAPENABLE] => 0
    [GIFTWRAPNAME] => 
    [GIFTWRAPAMOUNT] => 0
    [BUYEREMAILOPTINENABLE] => 0
    [CUSTOMERSERVICENUMBER] => 
    [BRANDNAME] => Outlet Season Scentia
    [PAYMENTACTION] => Sale
    [ALLOWNOTE] => 1
    [LANDINGPAGE] => Billing
    [NOSHIPPING] => 0
    [RETURNURL] => https://www.theoutletseason.com/scentia/ipn_main_handler.php?type=ec&zenid=ajak84gdhrp2hmcevsgpg8aso6
    [CANCELURL] => https://www.theoutletseason.com/scentia/shopping_cart.html?ec_cancel=1&zenid=ajak84gdhrp2hmcevsgpg8aso6
    [PAGESTYLE] => Primary
    [METHOD] => SetExpressCheckout
    [USER] => darogauruguay_api1.movinet.com.uy
    [PWD] => ****************
    [VERSION] => 61.0
    [SIGNATURE] => ****************************************************kSMn
)


Response: 
Array
(
    [TOKEN] => EC-68E765982M122483S
    [TIMESTAMP] => 2019-02-13T17:07:35Z
    [CORRELATIONID] => 33a8749251992
    [ACK] => Success
    [VERSION] => 61.0
    [BUILD] => 51861407
    [CURL_ERRORS] => 
)
</p>
Because these debug log was way too long and it kept repeating the same steps 2 or 3 more time, and then finally it displayed the last part, but not transaction, no sale ...
So that keeps me wondering if this was a hacking attempt, or an error in the plugin or the configuration????

Really not sure why this is happening ...

but the domain is from an authorized country ... Germany