After OS (Debian) upgrade invoice crons dont send emails

[elh]

Hi,
Invoices are generated  when cron is executes but invoices are not sent.
Error log has Exception: IMAGE Error (templates/..2.png): Could not find image file IN /httpd/billing../hbf/libs/mpdf/mpdf.php(11752), stack trace: #0 /httpd/billing...hbf/libs/mpdf/mpdf.php(11831): mPDF->_imageError('templates/naine...', true, 'Could not find ...') #1 /httpd/billing....hbf/libs/mpdf/Tag.php...
When using http:// ....png gives error but not with https://.
Also  unpaid invoices are not sended.
On clients invoice  page sending works.