Hey there @nurelm
I'm having a similar issue here, but it seems like its the Mailer built-in to PrestaShop which is having the issue? Thoughts?
Warning: require_once(/var/www/abc.com/modules/avalaratax/sdk/classes/AvaCert2Svc/Swift_Attachment.class.php): failed to open stream: No such file or directory in /var/www/abc.com/modules/avalaratax/sdk/AvaTax.php on line 22
Fatal error: require_once(): Failed opening required '/var/www/abc.com/modules/avalaratax/sdk/classes/AvaCert2Svc/Swift_Attachment.class.php' (include_path='/var/www/abc.com/tools/htmlpurifier/standalone:.:/opt/rh/php55/root/usr/share/pear:/opt/rh/php55/root/usr/share/php') in /var/www/abc.com/modules/avalaratax/sdk/AvaTax.php on line 22
Edited for completeness:
php version: 5.5.21
PrestaShop: 1.6.1.5
AvaTax: 3.5.7
I too was having this issue a month or so ago, but now I don't even have tax showing up on my checkout page -> Payment. Will be curious to see if anything is coming of it. Since I have a different issues, I'll be posting about that one too - no tax being displayed at all.