HTTP 500 error on PayPal site

I have this error . I made a log and here are the last information. Can somebody help me please? Thanks.

Feb-18-2010 07:45:00
termEC-10
Redirecting to checkout_process - Stack: header
Message:
Session Data: Array
(
[securityToken] => 342xxxxxxxxxxx073fec
[customers_host_address] => modemcable1xxxxx20-96.mc.videotron.ca
[cartID] => 71442
[cart] => shoppingCart Object
(
[contents] => Array
(
[12:824bbaba5539b2d3abce796fbe21c7b5] => Array
(
[qty] => 1
[attributes] => Array
(
[5] => 1
[2] => 3
[4] => 10
)

                    )

            )

        [total] => 1
        [weight] => 2
        [cartID] => 71442
        [content_type] => physical
        [free_shipping_item] => 0
        [free_shipping_weight] => 0
        [free_shipping_price] => 0
        [observers] => Array
            (
            )

    )

[navigation] => navigationHistory Object
    (
        [path] => Array
            (
                [0] => Array
                    (
                        [page] => index
                        [mode] => NONSSL
                        [get] => Array
                            (
                                [type] => ec
                                [token] => EC-05xxxxxM95171716
                                [PayerID] => DBAxxxxMN3QP2
                            )

                        [post] => Array
                            (
                            )

                    )

            )

        [snapshot] => Array
            (
            )

        [observers] => Array
            (
            )

    )

[check_valid] => true
[language] => english
[languages_id] => 1
[languages_code] => en
[currency] => CAD
[today_is] => 2010-02-18
[updateExpirations] => 1
[session_counter] => 1
[customers_ip_address] => xxxxxx.116
[customer_id] => 6
[customer_default_address_id] => 6
[customers_authorization] => 0
[customer_first_name] => Joxxxyne
[customer_last_name] => xxxxxx
[customer_country_id] => 38
[customer_zone_id] => 76
[valid_to_checkout] => 1
[sendto] => 6
[payment] => paypalwpp
[shipping] => Array
    (
        [id] => freeoptions_freeoptions
        [title] => Free Shipping Options (Free Shipping)
        [cost] => 0
    )

[billto] => 6
[shipping_tax_description] => 0
[shipping_tax_amount] => 0
[cot_gv] => 0
[comments] => 
[cart_errors] => 
[new_products_id_in_cart] => 12:824bbaba5539b2d3abce796fbe21c7b5
[paypal_ec_markflow] => 1
[paypal_ec_token] => EC-05Dxxxxxxxxxxx5171716
[paypal_ec_payer_id] => DBA4xN3QP2
[paypal_ec_payer_info] => Array
    (
        [payer_id] => DBA4xxx3QP2
        [payer_email] => xxxxxxxxxxx.ca
        [payer_salutation] => 
        [payer_gender] => 
        [payer_firstname] => Jxxxne
        [payer_lastname] => xxxxx
        [payer_business] => 
        [payer_status] => verified
        [ship_country_code] => CA
        [ship_address_status] => Unconfirmed
        [ship_phone] => xxxx
        [ship_name] => xxxxxxxxxxxx
        [ship_street_1] => xxxxxxxx
        [ship_street_2] => 
        [ship_city] => xxxxx
        [ship_state] => QC
        [ship_postal_code] => xxxxxxxxx5
        [ship_country_name] => Canada
    )

[paypal_ec_temp] => 

)

=================================

I forgot to mentionned when I have the error 500 a message appear saying refresh the page.

When I refresh the page a paypal box appears saying Sorry your last action could not been completed. Press the paypal icon.

When I press the paypal icon I am back to my paypal account (the buyer account not the business account).

Does somebody have ideas of what it is happening?

Thanks for your answer.

Where in the process do you receive the 500 error?

After I accept the payment in Paypal web site. As I mention when I click on the option offered after I and up in my paypal ( the one that accept the payment)
Thanks.

And as you posted in the " PayPal Express" forum can we assume that you are using PayPal Express?

If so post your module settings insuring that you X Out the sensitive data
DO NOT OPENLY post your token pass etc

Thanks for your time. Here the information hopefully it is what you want.
Enable Paypal true
sort order 0
payment zone none
set order processing(2)
Set unpaid pending (1)
set refund ** pending**
Express checkout requi confirmation no
Express checkout selec shipment no
express checkout skip payment page no
Express checkout automatic acc creation yes
Payment action final sale
Transation currency none
Payment page style primary
Api
api
api

Paypal mode Paypal
Debug mode **log file **

Is your Transation currency really none?

Yes the currency is none.

icikite:

After I accept the payment in Paypal web site. As I mention when I click on the option offered after I and up in my paypal ( the one that accept the payment)
Thanks.

So, this is all happening ON the PayPal site? If so, I suggest logging a ticket with them, since they control their site. http://www.paypal.com/mts

Ok I will log a ticket with them. When they wil found the problem I will let you know.
Thanks everybody.

Finally I find the error . It was a sentence in functions_taxes.php that is wrong and I still don't no why. If somebody have an idea it will be appreciate. The last sentence give me an error.( $tax is the value that cause the error. Strange because it was tested > then 0 before calling the las functions)
Thanks.

////
// Add tax to a products price based on whether we are displaying tax "in" the price
function zen_add_tax($price, $tax) {
global $currencies;

if ( (DISPLAY_PRICE_WITH_TAX == 'true') && ($tax > 0) ) {
       return zen_round($price, $currencies->currencies[DEFAULT_CURRENCY]['decimal_places']) + zen_calculate_tax($price, $tax);
} else {
  return zen_round($price, $currencies->currencies[DEFAULT_CURRENCY]['decimal_places']);
}

}

// Calculates Tax rounding the result
function zen_calculate_tax($price, $tax) {
global $currencies;
// $result = bcmul($price, $tax, $currencies->currencies[DEFAULT_CURRENCY]['decimal_places']);
// $result = bcdiv($result, 100, $currencies->currencies[DEFAULT_CURRENCY]['decimal_places']);
// return $result;
return zen_round($price * $tax / 100, $currencies->currencies[DEFAULT_CURRENCY]['decimal_places']);
}

You have found that error since Feb 21st and still no fix ... I have the same for the last couple of days ...

I hope someone figures this out ...

The error was happening in the function_taxes.php and here is the change I made:

Here what I change in function_taxes.php around line 170 (in bold)

// Calculates Tax rounding the result
function zen_calculate_tax($price, $tax) {
global $currencies;
// $result = bcmul($price, $tax, $currencies->currencies[DEFAULT_CURRENCY]['decimal_places']);
// $result = bcdiv($result, 100, $currencies->currencies[DEFAULT_CURRENCY]['decimal_places']);
// return $result;
**if ( (is_numeric($tax) == 'true') && ($tax > 0) ) {

return zen_round($price * $tax / 100, $currencies->currencies[DEFAULT_CURRENCY]['decimal_places']);** }
}

I submit that the approach you've taken there will result in further problems if the $tax value is not numeric. Namely, what you've done there prevents any value from being returned, which means whatever asked for a tax calculation is going to get no results, thus resulting in incorrect calculations, and possibly even mismatched transaction/order amounts.

Upon further investigation, the only reason for $tax not being numeric would be if you had entered non-numeric data for the tax rate when you set up your tax rates in your admin area.

.. which begs the question. How exactly are your tax zones and tax rates set up?

Here are my taxe rate:

Priority Tax Class Zone Tax Rate Action
1 Taxable Goods Canada GST zone 5.0%
1 Taxable Goods HST tax zone 13.0%
2 Taxable Goods Quebec PST zone 7.5%
1 Shipping Canada GST zone 5.0%
2 Shipping Quebec PST zone 7.5%
1 Shipping HST tax zone 13.0%
Displaying 1 to 6 (of 6 tax rates)

Taxe zone
GEND: : Taxes & Zones Defined : Zones Defined but not Taxes : Not Configured
Zone Name Zone Description Status Action
Canada GST zone GST (except: NS,NB,NL)
Florida Florida local sales tax zone
HST tax zone NS,NB,NL
Quebec PST zone PST( only when shipping to Quebec)
Displaying 1 to 4 (of 4 tax zones) Page 1 of 1

Notice that I had the problems only when returning from paypal. All taxes seams correct.