Filr 4.0 ALL-IN-ONE upgrade from Filr 3.4.3

Everything went smooth. I can login as vaadmin and as root at https://<IP>:9443. There I can do all there is to do.
But when I try to login with https://<IP> or https://<IP>:8443 as admin I get an error "(kablink) Could not open index writer".
First of all I do not understand, why the admin passord has got lost during migration.

I found TID 7012569 ( which is for MySQL.
Logged in as vaadmin and using the phpPgAdmin icon, choosing the database filr, I could manage to use the sql statement
select name,password from SS_Principals where name='admin';
from the TID but not the reset command
UPDATE SS_Principals SET password='uQgmrEdsBQnB/HOh1w87ooxE5a66U5u/Y5k2EIlNJLw=' WHERE name='admin' and type='user';
There I get

ERROR: syntax error at or near "SET"
LINE 1: ...LECT COUNT(*) AS total FROM (UPDATE SS_Principals SET passwo...

I'm not fit with SQL ... :-(

Does anyone know how I can reset the admin password (or what I did possible wrong during upgrade to 4.0)?

Best regards, Uwe.