Error Message

Error
Sorry, Registration is enabled, free registrations are not allowed, but no subscription plan is available for registration. Please contact site administrator.

I do not understand why i am getting this error message when a new user attempts to sign up. I have set up another subscription and it is free and open to the public to register.to access content.

You have free registrations without a subscription disabled within CBSubs > Settings > Global, but you don't have a plan available for the user to subscribe to. If you do have a plan available and it's a free lifetime plan then ensure free lifetime plans are configured to create subscriptions within CBSubs > Settings > Global.

I have two plans.
#1 (primary) for registered members with yearly paid subscriptions. Free is not an option. These subscribers need to also be a subscriber of plan #2 as they will also be exhibiting at the event.
#2 is for a FREE 3 month membership to the general public for an event that requires subscription records for exhibitors and need to get emails from the administrator. These subscribers may Upgrade to plan #1 but do not automatically have the registered access as plan #1. They will be considered "Guest".

It never occurred to me to look in configuration settings thank you. But now it leaves me more confused as we do not offer a free lifetime subscription plan and "allow free registered users (without subscription), we need the free user to subscribe so we can email them.

They will be considered "Guest".

No sure I understand. You're setting their usergroup to Guest? That won't work as Guest has no login permission. They still need to have Registered usergroup. You maybe hitting an ACL issue where once they attempt to register their permission isn't high enough to access the plan and thus can no longer subscribe to it resulting in no plan being selected basically.

Okay, so they need to be registered. But if both plans are registered access and most of my articles and modules are set up for registered only then they have the same access upon login as a registered member from plan #1. The registered user from plan #2 will see everything registered members from plan #1 sees. Correct?

How do I prevent #2 registered user from seeing everything #1 registered user sees but still allow #1 registered user to see everything #2 registered sees?

#1 registered user should have full access to content of site including event content.
#2 registered user only has access to specific content related to the event.

Create new usergroups for your higher access permissions. Then create a view access level for them. Now protect your content with that view access level. Next assign your custom usergroup within your paid plans under the access tab so users are given that usergroup when they subscribe. Alternatively protect your content using CBSubs Content, which can protect Joomla articles directly, modules, extensions, menu items, or even URLs.