WP Social Login doesn't work on WPEngine
If you've seen this error while trying WP Social Login and you're hosted by WP Engine, most likely you need to ask them to disable the Login Protection, which is an option on their end that protects against brute force. The protection can cause conflicts with plugins or functions that customize the login process.
Normally you need to disable mod_security, or try to whitelist the WSL endpoint, but WP Engine doesn't use mod_security.
"WP Engine does not use the mod_security Web Application Firewall (WAF) with Apache. Instead, we use a proprietary traffic detection and blocking system among other enterprise-grade security measures. This firewall will automatically block IPs or User Agents based on a predetermined set of rules."