Certain Magento Pages returning HTTP Error 500

Question

Undergoing a Server Migration and Magento has been an issue. The page works just fine but every time that someone clicks on "Check out with PayPal", "PayPal Credit", or "Checkout with other options", it return HTTP Error 500 saying that the page is unable to handle the request.

Unable to Handle Request

This also happens on the back-end when an Administrator tries to access "PayPal Methods" under "Sales" and last but not least when we try to access an order. A few hours ago, orders would return an error specifying that it no longer existed when you clicked on it. I checked the sales_flat_order table on the database and it was empty. However, I imported all the data that should be in there and now it returns the same HTTP 500 Error.

For the most part, everything else has somewhat worked as it should. Memory has been increased in .htacces, I have tried messing with permissions according to this, nothing works.

find . -type f \-exec chmod 644 {} \;
find . -type d \-exec chmod 755 {} \;
find ./var -type d \-exec chmod 777 {} \;
find ./var -type f \-exec chmod 666 {} \;
find ./media -type d \-exec chmod 777 {} \;
find ./media -type f \-exec chmod 666 {} \;
chmod 777 ./app/etc
chmod 644 ./app/etc/*.xml

Answer 1

The 500 error could be almost anything - from an incompatible PHP version, to errors in the htaccess file.

Your best bet is to check your webserver's error logs.

• Lisandro Grullon: I've tried looking at the error_log file in the main directory but it doesn't update. Last time that file updated was in May of 2016, is there a way it has to be enabled or something?
• Lisandro Grullon: Actually, I was able to find the log. I fixed part of the issue thankfully. I still cannot review orders: Error I am getting is the following: SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails