Stripe Error Or Stripe Not Defined During Checkout

This is a random issue that rarely happens.

The first thing you need to do is ensure your computer/operating system and browser are completely up to date. Also, make sure javascript is enabled in your browser.

Then try again.

If that still doesn't work, try using a different browser. Chrome or Firefox tend to work the best.

If you're still running into problems, I'd give it a shot on a different device.