This article explains the reason why a BGP session may get stuck in the 'Connect' state when configuring new Tenant systems using MD5 authentication

When configuring a new tenant with a routing instance and BGP using MD5 authentication via the following command:

set tenants <tenant-name> routing-instances <instance-name> protocols bgp group <group-name> authentication-key <key>

and committing the configuration, the MD5 authentication setting is expected to be applied. However, after the commit:

• MD5 authentication is missing from the configuration.
• Incoming BGP packets containing MD5 authentication are dropped, as the local system does not recognize the MD5 key.
• As a result, the BGP session remains stuck in the 'Connect' state and fails to establish.

This is a known issue and has been addressed in Junos version 25.4R1.

Workaround:

If you encounter this issue after configuring a new tenant with MD5 authentication:

• Instead of using a standard commit, perform a commit full.
  This ensures that the MD5 authentication settings are properly applied to the configuration.