Random errors when adding product to shopping cart

[andrzejdlugosz]

Hello,

When trying to add a product to shopping cart I am getting error:

 

Impossible to add the product to the cart.

textStatus: 'error'

errorThrown: ''

responseText:

 

Once the error occur I am getting further errors:

 

TECHNICAL ERROR: unable to save update quantity Details: Error thrown: [object Object] Text status: error

ERROR: unable to delete the product

 

I don't know what causes errors, and where to look for solutions. Can anyone help?

Thank you.

[vekia]

case needs inspection of shop with developer tools.

please share url to shop,

and enable error reporting.

[andrzejdlugosz]

Thank you for your reply.

Url to shop:

http://sit-stand.com/

 

I define:  

define('_PS_MODE_DEV_', true);

in defines.inc.php

Now I have had trouble causing an error but after few tries in fancybox window:

 

Impossible to add the product to the cart.
textStatus: 'error'
errorThrown: ''
responseText:

 

and in developer tools:

 

Failed to load resource: net::ERR_EMPTY_RESPONSE 

http://sit-stand.com//modules/paypal/express_checkout/ajax.php?get_qty=1&id_product=16&id_product_attribute=5019&_=1422570635251 Failed to load resource: 

http://sit-stand.com/?rand=1422570636584 Failed to load resource: net::ERR_EMPTY_RESPONSE