Browser compatibility changes to comply with PCI mandate
The Payment Card Industry Security Standards Council (PCI SSC) has mandated that all credit card processors must retire version 1.0 of an encryption method called TLS (Transport Layer Security).
To comply with this directive, and ensure the highest standards of security and data integrity, Wild Apricot will stop supporting TLS versions 1.0 and 1.1 on March 12, 2018, but will continue to support TLS version 1.2. However, some older browser versions do not support TLS 1.2, so visitors to your Wild Apricot site may have to upgrade their browsers if they want to make payments on your site.
To view a list of browsers versions that support TLS 1.2 and higher, see https://support.wildapricot.com/hc/en-us/articles/360000599828-Browser-compatibility-changes-to-comply-with-PCI-mandate
You should encourage visitors to your site to check their browser version against this table.