3484780 - 'Ticket logon failed' while accessing a firefighter session

Attempting to use the Firefighter user for access results in the following error:

"500 Internal Server Error 
Ticket logon failed"

The URL of the page where the error occurs has the path /sap/public/myssocntl

The SM50 traces have the following:

N  myssocntl: logon and do not create logon ticket
N  Get_RefUser(<Client number>,<Firefighter user>) =>
N  password logon is generally enabled (default)
N  initial password is still valid (expiration period=7 / days gone=0)
N  password change required (initial password)
N  save user time zone = >      < for user ><Client number>> / ><Firefighter user>   > into spa
N  DyISignR(): return code=0 "Logon successful" (see note 320991)
H        SignOn Signon procedure (rc: 0, saprc: 1)
N  myssocntl: logon not successful
H  HTTP> ab_HttpErrorHandler (role: 2, protocol: 2, error: Ticket logon failed (see trace (SAP Note 495911)))

myssocntl, icf/reject_expired_passwd, Firefighter,  FFID, 500 Internal Server Error, Ticket logon failed  , KBA , BC-SEC-LGN , Authentication , GRC-SAC-EAM , Emergency Access Management , Problem