To drag up an earlier thread about adding SCA support,

Quote Originally Posted by RocketSites View Post
With the assistance of @Congerman, I have made some changes to the Square module with a view to achieving SCA compliance.

The following is ready for TESTING - use AT YOUR OWN RISK. Replace these two core files with those included in the archive:

/includes/modules/pages/checkout_payment/jscript_square.php
/includes/modules/payment/square.php

No need to un-install and then re-install the module in admin, as there are no DB changes.

https://www.rocketsites.co.uk/square.zip
I'd be very interested in looking over this solution as we are seeing increasing "requires verification" failures from Square as the number of cards requiring 3DS/SCA increases. However, the original file is no longer at the above URL. Are you able to make it available again please, RocketSites, or does someone else have a copy they can post?