'Exception' with message 'Warning: Division by zero in vendor/magento/module-sales/Model/Order/Creditmemo/Total/Discount.php on line 32' in vendor/magento/framework/App/ErrorHandler.php:61

[lsv]

Preconditions

1. Magento 2.1.1

Steps to reproduce

1. Create a order with 0$ in shipment
2. Complete the order
3. Create new creditmemo
4. Add something in "Refund shipping"

Expected result

1. I would suggest a error "You can not refund shipping when shipping is zero"

With the current error message the admin would try to create this creditmemo for long time, because the error is so "Try again later..."

Many errors around the site is just

try {
  ... massive code ...
} catch {
  ... Try again later ...
}

Actual result

1. We can't save the credit memo right now.

[viktym]

Hi @lsv
We've created internal ticket MAGETWO-59136 to address this issue.
Thanks for the feedback.