Thrive Apprentice Cookie Nonce Is Invalid errors are easy to fix.
Nonce: A time-varying value that has at most a negligible chance of repeating; for example, a random value that is generated anew for each use, a time-stamp, a sequence number, or some combination of these. It can be a secret or non-secret value.
WordPress nonces are defined as: … a “number used once” to help protect URLs and forms from certain types of misuse, malicious or otherwise. WordPress nonces aren’t numbers, but are a hash made up of numbers and letters. Nor are they used only once, but have a limited “lifetime” after which they expire. During that time period the same nonce will be generated for a given user in a given context. The nonce for that action will remain the same for that user until that nonce life cycle has completed.
WordPress’s security tokens are called “nonces” despite the above noted differences from true nonces, because they serve much the same purpose as nonces do. They help protect against several types of attacks
This happens because the validation token — a WordPress nonce — could not be verified. This happens mainly because a caching plugin such as W3 Total Cache (W3TC) or CDN, such as Cloudflare is in use and caches the pages for longer than the WordPress nonce life — by default 12 hours. This might be caused by a caching system provided by your host. In that case, request that your host exempt the page with your page from the cache.
Fixing “Cookie Nonce Is Invalid” Error
You will see this error when you leave the Editor screen of your Thrive Apprentice course open for an extended time period. When this happens, your cookie will expire and you get error after you try to save your changes. Your recent changes will be lost.
To fix this issue, open the Thrive Apprentice tab again, this will create a new cookie.
If that doesn’t work, log out of your site’s WP-Admin dashboard, and then log back in.
You may also need to close/refresh other open tabs of your dashboard.
That should fix it.
For permanent fix, set a cache exclusion for the page or set a cache life of less than 12 hours. A caching system that sets a cache length longer than 12 hours is going to cause problems with any type of front-end form, including comment forms. You should always configure a WordPress static HTML cache to last no longer than 12 hours.