Validate in backups remote destination fails on AlmaLinux 10 in the UI.

Symptoms

Clicking Validate on remote destination in Backup Configuration fails on RHEL 10+ servers (AlmaLinux 10).

Description

While attempting to create a cPanel backup with a remote destination and attempting to validate, it will possibly fail validation with the following error:

Error: Validation for transport “nova.siteocity.com” failed: 
Can't ssh to backup2.siteocity.com: unable to establish master 
SSH connection: master process exited unexpectedly at 
/usr/local/cpanel/Cpanel/Transport/Files/Rsync.pm line 261.

Manually validating the remote destination works fine:

whmapi1 backup_destination_validate id=UNIQUE_ID disableonfail=0
---
data:
  id: UNIQUE_ID
metadata:
  command: backup_destination_validate
  reason: OK
  result: 1
  version: 1

We've opened an internal case for our development team to investigate this further. For reference, the case number is CPANEL-52616. Follow this article to receive an email notification when a solution is published in the product. 

Workaround

None known of at this time.