Internal Server Error - PayPal transactions suddenly failing

Hi,

My client's cart has been working fine for over a year now, and was successfully processing orders up to the 25th September. Over the weekend the site has suddenly stopped processing orders, and the ipn_main_handler.php page is coming back with this error message:

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, root@localhost and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

As far as I'm aware nothing has been changed on the site, and the vagueness of the message really isn't helping. If I simply view the page without sending any data across I just get a message "Nothing to process. Please return to homepage." The page is http://www.turnerscabin.co.uk/ipn_main_handler.php. I've had a look at the curltester.php page (http://www.turnerscabin.co.uk/extras/curltester.php) and I get the Internal Server Error message again. But cURL is enabled.

Can anyone suggest what is going wrong and how I can fix this?

Thanks in advance

Some info here:

http://www.zen-cart.com/content.php?105-why-am-i-getting-500-internal-server-error

I'm having exactly the same problem on my site. If you've found a solution please post it here. I've contacted both PayPal and my host provider, but so far I've not had a response from PayPal (now over 24hrs) and my host provider gave some error logs which didn't seem relevant.

Have either of you contacted your hosting company and asked for a copy of the server logs?

stevesh pointed you to an extremely valuable article explaining more of what you need to know.

DrByte:

Have either of you contacted your hosting company and asked for a copy of the server logs?

stevesh pointed you to an extremely valuable article explaining more of what you need to know.
The only reply from my hosting company (so far) has been to provide these snip-its of the log files:

[Sun Sep 16 03:20:37 2012] [error] [client 210.188.212.201] File does not exist: /home/linweb06/3/3d-kits.co.uk-1035097136/user/htdocs/online-shop/admin/sqlpatch.php
[Sun Sep 16 03:20:39 2012] [error] [client 210.188.212.201] File does not exist: /home/linweb06/3/3d-kits.co.uk-1035097136/user/htdocs/online-shop/admin/record_company.php
[Mon Oct 01 12:00:30 2012] [error] [client 157.55.33.181] File does not exist: /home/linweb06/3/3d-kits.co.uk-1035097136/user/htdocs/robots.txt

The files requested are indeed missing, but as they are in redundant directories (which have been redundant since go-live 12 months ago) I'm at a loss to know why they were requested.

My failure of PayPal Express has happened at the same time and in the same way as kazbryan's, suggesting some external problem. I notice that my problems started at about the same time as PayPal was reported to be having technical problems with withdrawals. I'm still waiting for a response from PayPal. Meanwhile I'll request a complete set of server logs for the last seven days from my hosting company.

Update: I've had a message from my hosting provider (Fasthosts) which suggests this is a wider system problem that they are working with PayPal to resolve.

hi i have had the same problems which you can read here http://www.zen-cart.com/showthread.php?200720-mod_fcgid-ap_pass_brigade-failed-in-handle_request-function.

and an update from them
Further to recent communication - there are some network issues between PayPal and Fasthosts that are being led by PayPal at the moment. This is causing the symptoms that you describe. I am afraid I don't have an eta for resolution at the moment. We are unable to effect the necessary remedy as PayPal need to carry out investigative work.

update
got email from fast host saying they had fixed it and mine is now up and running again :D

is every one elses ok now??