If Finch ever loses a connection with an employer’s provider system, we will return a 401 Unauthorized HTTP status code with a finch_code of reauthenticate_user (see Finch API errors). 
{
  "code": 401,
  "name": "authentication_error",
  "finch_code": "reauthenticate_user",
  "message": "Please reauthenticate user"
}
If an access token is returning this error, follow the reauthentication process to reconnect the employer.