Cannot establish a secure connection with the CUPS Web user interface

Issue

• We keep getting alerts from because of the following errors in the CUPS error_log:

  E [04/Mar/2021:08:43:01 -0500] error:14094416:SSL routines:ssl3_read_bytes:sslv3 alert certificate unknown
  E [04/Mar/2021:16:51:00 -0500] Unable to encrypt connection from 10.100.0.79.
  

• In RHEL 6, we are receiving the following errors in the CUPS error_log:

  E [25/May/2021:12:30:23 -0400] Unable to encrypt connection from 10.146.100.12 - A TLS fatal alert has been received.
  

• Whenever we try to connect to CUPS via the https:// URI to perform administrative functions, our Chrome browser shows an error like the following:

  https://10.1.8.4:631/admin
  
  This site can’t provide a secure connection
  10.1.8.4 sent an invalid response.
  Try running Windows Network Diagnostics.
  ERR_SSL_PROTOCOL_ERROR