Unable to Verify $_POST Vars Error

There are two main things to try when fixing this error:

Server Scanner

This script will help spot some known server issues that would cause you this error. Knowledge Base » s2Member Server Scanner

Follow the instructions in that article to spot these issues, and follow the advice given to solve each until you get an all-green report.

PayPal PDT

That setting would cause this error if it’s missing or incorrect. Please verify that your PDT configuration is correct. Dashboard -› s2Member -› PayPal Options -› PayPal PDT Integration

After fixing each one, do a new test purchase to see if the error is gone.

If you continue having this issue, try these other tips to help solve the issue: Knowledge Base » Common Troubleshooting Tips