Thanks for the tips on upgrade. I have successfully upgraded to Magento 18.104.22.168. After upgrade, the invoice and ship emails are not working from the admin console. Clicking on 'Submit Invoice' (with 'Email copy of invoice' checked) takes to a blank 500 page.
After debugging, it seems that
method is causing the issue. The method is not returning. The method is present in code/core/Mage/Sales/Model/Order/Invoice.php.
Any clue on what could be the issue ?
Being a developer for warmoven.in, this feature has got an important place on my website and I hope to fix the issue soon.