ERROR MESSAGE: Session expired or cookies are not enabled in your browser.

I am about to lose my mind!:dry: I am getting the following error when anyone try's to register on my website:

Session expired or cookies are not enabled in your browser. Please press "reload page" in your browser, and enable cookies in your browser. Please refresh/reload page before filling-in.

If I try adding a user from the backend admin I get this error

COM_CMC_SUBSCRIBE_FAILED 404

I have turned off SEO, SEF and any related plugin, I have disabled dozens of plugins overall and still get the above error when trying to register on the website. This seems to havel started after updating to 3.9.16. I deactivated Admintools component and more, tried multiple browsers, cleared cache on site and browsers repeatedly and still no go - Same ERROR! uhg... I have been troubleshooting for 7 hours and at my wits-end.

When I enable debugging there is "no" errors given. So, I am not even sure where to look. Could someone please help me?

CURRENT SITE SYSTEM

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PHP Built On Linux p3plvcpnl28048.prod.phx3.secureserver.net 2.6.32-673.26.1.lve1.4.30.el6.x86_64 #1 SMP Wed Jun 21 19:37:37 EDT 2017 x86_64
Database Type mysql
Database Version 5.6.44-cll-lve
Database Collation utf8_general_ci
Database Connection Collation utf8mb4_general_ci
PHP Version 7.3.14
Web Server Apache
WebServer to PHP Interface litespeed
Joomla! Version Joomla! 3.9.16 Stable [ Amani ] 10-March-2020 15:00 GMT
Joomla! Platform Version Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
User Agent Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.1 Safari/605.1.15

I am about to lose my mind!:dry: I am getting the following error when anyone try's to register on my website:

The spoof checking (CSRF check) is failing. That really shouldn't be possible anymore. Previously we were using a separate cookie for this, but now it's just kept in Joomlas session so the only way it can fail now is if Joomlas session failed or the page you're viewing output a cached view where the spoof check is out of date (shouldn't be possible as we purge page cache for CB views). Please ensure CB is completely up to date.

If I try adding a user from the backend admin I get this error

That's not coming from CB. You've something installed acting on Joomla user store events. COM_CMC is the clue what component it is. Specifically whatever CMC stands for. Are you using the below extension by chance?

extensions.joomla.org/extension/cmc/

Try unpublishing it and any of its plugins in Extensions > Manage.

Well, I have been unable to resolve this error still "Session expired or cookies are not enabled in your browser. Please press "reload page" in your browser, and enable cookies in your browser. Please refresh/reload page before filling-in." I attached screen shot of the error

I disabled CMC that worked for the backend error.
Joomla was and is up to date. I verified everything today.
I spent another 6 hours today trying to resolve this, and have no clue what the cause is as even in debug mode it shows no errors.
Site Cache is off
Empty browser cache and refreshed each time
Turned off Admin tools.
disables dozens of plugins

Yet it still fails. This did not start occurring until after I updated community builder a few months back. Before then it worked fine.

I get the same issue with a client site.
The client site has been up and running for over 7 years without this issue then they started reporting that some users are experiencing it and they have had to register the users directly via the admin to resolve the inability for people to register, but this is unsustainable and they must be losing a lot of potential business.
I have been through all the threads.
Tried all the things that have been recommended but still no joy.
I can sometimes recreate but it's fairly random.
I can have the issue in firefox but not in chrome one day and chrome but not firefox another. I can refresh the browser and it clears, then refresh the browser another day and it does not clear.
If it affects the email then it will also affect the username and visa versa.

It's now a good steady 10% of users that report with this problem.
On last community builder and Joomla and have persisted with it for a good 6 months hoping that community builder update will fix it. Any help gratefully received.
It happens with ajax so as soon as the mouse clicks away from the fields
URL with the issue is
www.lawinsport.com/registration

It's probably your cookie policy extension tampering with Joomla session cookie. Those don't need to block session cookies. Session cookies are explicitly exempt from GDPR. If this is happening reliably on a clean installation then I can review the issue further, but as it stands it's entirely an issue that's a product of your environment tampering with cookies or sessions. We don't use a separate cookie for CSRF tokens anymore. It's entirely stored in the Joomla session that Joomla creates when a user visits the site. Try disabling any cookie policy extensions, switch to default Joomla template, disable and clear cache, then see if that resolves it.

Thanks for your suggestion. I do not have any cookie policy extensions installed. I have been digging regarding anything related to cookies or plugins or components that might be involved. I have still not found the root cause. I have reinstalled CB but not a full Joomla site reinstall. I have disabled my .htaccess file and turned off site cache and nada.

Here is one glimmer of hope or interest. When I login as another user and then log out. Clear Website Cacheing on the browser/and Joomla site and refresh browser I am able to complete the form without error. I can also complete the form without error without any clearing of cacheing. I find this interesting that I can complete the form without error after logging in then logging out, but no other time. Do you see any connection in this or a cause?