Authorize.net's API indicates a character limit of 255 characters on the 'description' parameter. However, the plugin does not trim the string. This can potentially result in failed transactions.
The issue is only evident if you're selling multiple products on a single form, and these products have very long names/labels.
2018 marked the "End of Life" for PHP 5.6 and 7.0. In the very near future, PHP 7.1 will come to it's "End of Life". You may have seen the big red warning on your Joomla administrator panel regarding the upgrade and may have even attempted at upgrading PHP yourself only to have your Joomla site crash (blank page).
You may have recently seen PHP 5.x warnings in your Joomla Administrator Control Panel. According to PHP.net, PHP 5.6 support will come to an End of Life on December 31, 2018.
Have you tried to upgrade Joomla to latest version from 3.7 or older installations with no luck? Here is useful tip to manually upgrade your Joomla website.
cPanel hosting hacked by malware called Cloki? IDL Web Inc. has the fix that can help you protect your hosting account from being taken down due to Cloki overloading server by running multiple processes concurrently..