Logged in user can't add products in cart :/

[ereallstaff]

Hello on our www.modacalcio.it ( VM 2.6 Joomla 2.5 ) when user is logged in , sees the cart empty , and after adding product to cart the routing steps back to homepage

What can be the problem?

[Studio 42]

FIrst to do is solving your bad image links.
This is the report in home:

Mixed Content: The page at 'https://www.modacalcio.it/en/'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/LogoTmp.gif';. This content should also be served over HTTPS.
(index):682 Mixed Content: The page at 'https://www.modacalcio.it/en/'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/images/whatsapp.jpg';. This content should also be served over HTTPS.
(index):1042 Mixed Content: The page at 'https://www.modacalcio.it/en/'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/images/banners/1000x350.jpg';. This content should also be served over HTTPS.
(index):1044 Mixed Content: The page at 'https://www.modacalcio.it/en/'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/images/banners/Centr2.jpg';. This content should also be served over HTTPS.
(index):1044 Mixed Content: The page at 'https://www.modacalcio.it/en/'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/images/banners/Saldi.jpg';. This content should also be served over HTTPS.
(index):1044 Mixed Content: The page at 'https://www.modacalcio.it/en/'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/images/banners/Centr1.jpg';. This content should also be served over HTTPS.
bg_dropline.png Failed to load resource: the server responded with a status of 404 (Not Found)

If you have same problem with javascript then this stop to load in some browser.
So check your console and modify your links.

In your details page :

Uncaught TypeError: window.addEvent is not a function
    at productDetailsUpdater.js:4
(anonymous) @ productDetailsUpdater.js:4
gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html:630 Mixed Content: The page at 'https://www.modacalcio.it/en/gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/LogoTmp.gif';. This content should also be served over HTTPS.
gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html:663 Mixed Content: The page at 'https://www.modacalcio.it/en/gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/images/whatsapp.jpg';. This content should also be served over HTTPS.
gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html:912 GET https://www.modacalcio.it/images/style1/bg_dropline.png 404 (Not Found)
gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html:1272 Mixed Content: The page at 'https://www.modacalcio.it/en/gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html'; was loaded over HTTPS, but requested an insecure image 'http://www.easycommercemanager.com/immaginiEbay/taglie/scarpebliddyspam.jpg';. This content should also be served over HTTPS.
gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html:1283 Mixed Content: The page at 'https://www.modacalcio.it/en/gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/images/stories/virtuemart/icon/satisf.jpg';. This content should also be served over HTTPS.
gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html:1293 Mixed Content: The page at 'https://www.modacalcio.it/en/gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/images/stories/virtuemart/icon/spediz.jpg';. This content should also be served over HTTPS.
gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html:1313 Mixed Content: The page at 'https://www.modacalcio.it/en/gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/images/stories/virtuemart/icon/customServ.jpg';. This content should also be served over HTTPS.
gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html:1317 Mixed Content: The page at 'https://www.modacalcio.it/en/gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html'; was loaded over HTTPS, but requested an insecure image 'http://www.modacalcio.it/images/stories/virtuemart/icon/return.jpg';. This content should also be served over HTTPS.
gymnastics-shoes-sneakers-original-bliddyspam-men-varial-low-skate-black-5400-detail.html:1261 GET https://www.modacalcio.it/en/templates/gk_esport/images/payments.png 404 (Not Found)
script.js:140 Uncaught TypeError: toggleBtn.getComputedStyle is not a function
    at Object.detect (script.js:140)
    at Object.i.extend.$owner (mootools-core.js:141)
    at Object.start (script.js:156)
    at Object.i.extend.$owner (mootools-core.js:141)
    at mootools-core.js:88
    at d (mootools-core.js:367)
    at e (mootools-core.js:368)

You use an obselete template or mootools is not loaded correctly.
So all your problem are because badly programmed modules or plugins an bad images links and poor template.
Best is to backup your website and try to upgrade all to Joomla 3.6.5 and Vm 3.0.18.6 and set correctly all your website
Regards,
Patrick

[ereallstaff]

Ok but why in guest checkout no problem and registered user have problem?

If like you say , should be work or not for both

Anyway will check , thank you

[Studio 42]

ereallstaff,
javascript can be the origin of your problem, so it's important. And the best way to check your problem is to temp switch your template to protostar and do a full checkout

[ereallstaff]

Nice suggestion

[ereallstaff]

the javascript error is in the megamenu module, but anyway can break probably something during checkout

With other template I need to enable login module first, will do a deep check later