Error during Open enrollment period for all plan types

Summary:

We have an Open Enrollment event and while employees are trying to enroll into different plans, we are seeing an error.

Content (required):

We have an Open Enrollment event and while employees are trying to enroll into different plans, we are seeing an error as below:

Can anyone help me on this issue?

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):