Error on coupon

[micropalla]

Hello.
This morning for the first time i tried to add a coupon.
Everything is ok, I click on save and it applies the coupon but unfortunately as I press on "Order Now" button nothing happens.
The page is refreshed in a continuous loop.
If I remove the coupon option the order goes on.

Which could be the problem?
Thx
Lorenzo

[GJC Web Design]

give a live url
turn on all error reporting and debug
check the browser console for JS errors
give versions
give info on the checkout

[micropalla]

I receive this message:

Notice: Undefined index: couponTax in /home/ufp0lqy4/domains/msaccessoriferroviari.it/public_html/templates/ot_mixshop/html/com_virtuemart/cart/default_pricelist.php

[jenkinhill]

Also:
give a live url
turn on all error reporting and debug
check the browser console for JS errors
give versions
give info on the checkout

[micropalla]

Ok

Live url: https://www.msaccessoriferroviari.it/ - the coupon is black
I did it
Version 3.4.2

[GJC Web Design]

the "error" you show is just a notice

you also have

Warning: Illegal string offset 'relative' in /home/ufp0lqy4/domains/msaccessoriferroviari.it/public_html/libraries/src/HTML/HTMLHelper.php on line 626 Warning: Illegal string offset 'pathOnly' in /home/ufp0lqy4/domains/msaccessoriferroviari.it/public_html/libraries/src/HTML/HTMLHelper.php on line 627 Warning: Illegal string offset 'detectBrowser' in /home/ufp0lqy4/domains/msaccessoriferroviari.it/public_html/libraries/src/HTML/HTMLHelper.php on line 628 Warning: Illegal string offset 'detectDebug' in /home/ufp0lqy4/domains/msaccessoriferroviari.it/public_html/libraries/src/HTML/HTMLHelper.php on line 629 Warning: Illegal string offset 'relative' in /home/ufp0lqy4/domains/msaccessoriferroviari.it/public_html/libraries/src/HTML/HTMLHelper.php on line 632 Warning: Illegal string offset 'detectBrowser' in /home/ufp0lqy4/domains/msaccessoriferroviari.it/public_html/libraries/src/HTML/HTMLHelper.php on line 632 Warning: Illegal string offset 'detectDebug' in /home/ufp0lqy4/domains/msaccessoriferroviari.it/public_html/libraries/src/HTML/HTMLHelper.php on line 632 Warning: Illegal string offset 'pathOnly' in /home/ufp0lqy4/domains/msaccessoriferroviari.it/public_html/libraries/src/HTML/HTMLHelper.php on line 635

which comes from an out of date template call to load css

and see screen

can checkout fine with a coupon on protostar

https://www.msaccessoriferroviari.it/index.php/carrello?template=protostar

[micropalla]

Thanks, I thought it was a Template problem