On MX platforms supporting subscriber services, PPPoE and DHCP subscribers are not able to connect on dynamic VLAN. This issue is a timing issue during which the SDB becomes unavailable and hence the session establishment fails for the subscribers.

In problematic state bbe-smgd trace log will show an error similar to (session ID will be different from 161372398):

ERR: dprof_process_request: Add pre_processing failure for client request from plugin: Central, session_id=161372398, err=57, uifl is inactive

The following error counters will be increasing in shmlog statistics:

user@root> show shmlog statistics logname all
<snip>
BBE_DPROF_P_ADD_PRE_PROCESS_FAIL    Jun 21 10:11:58.444287   357804
BBE_DPROF_P_PROCESS_REQUEST_FAILED  Jun 21 10:11:58.444290   357804

The issue has been resolved in PR1714778. You can find information about the releases containing this fix at https://prsearch.juniper.net/problemreport/PR1714778.

To recover from this state, please use the hidden command : 
 

request system subscriber-management release-session id <id>  ; where <id> refers to the session ID of the stuck VLAN IFL shown in the output of 'show subscriber interface <stuck_vlan_ifl_name>'.