Error in checkout while using Bitcoin Payments by BitcoinWay with WooCommerce, "CurveCurveFp Object"
FYI: this site seems to be using the Bitcoin Payments for WooCommerce plugin. If I'm wrong, then please disregard this answer.

This plugin is not compatible with the current version of Electrum. Give this a try (these instructions are for Windows):


Start -> Run (or press the Windows key + r), then type in %appdata%\Electrum\wallets and press OK.
Take a backup of all of your wallet files in this folder. If you have any funds in your wallet(s) and skip this step, you may lose those funds, so be careful!
Close this folder, and open a new one: Start -> Run (or press the Windows key + r), then type in %appdata% and press OK.
Delete the Electrum folder.
Uninstall Electrum.
Download and install electrum-1.9.8-setup.exe from https://download.electrum.org/.
Follow the normal install instructions for the plugin.


After you've tested it and have gotten it working, it is safe (and recommended) to upgrade Electrum to the newest version. You only need the old version when you first create your wallet. After upgrading, you can open your wallet backups you made in step 3 to access any old funds (but you can't use these wallets with the plugin).