lizmap-web-client: Maps do not display after login in PostgreSQL / Lizmap 3.4.0

I did an update and installed lizmap 3.4.0 in a new folder keeping the same structure of my old 3.3.3-version (following the instructions on https://docs.lizmap.com/current/en/install/upgrade.html#upgrading-from-lizmap-3-x-versions. Authetification is done trough PostgreSQL-database.

Without loging in, I’m able to display all public projects and open them without any issues (the Monpellier demo maps just open fine, as well as my own public maps). When I log in with my credentials (from the 3.3.3. version) accessing the same database, I can log in and all the projects are there and I can access the admin panel. When I try to open a map (even the Montepellier demo maps) it fails. I just see the map is loading with Lizmap-Logo. In the case I choose the Montpellier demo I can see the header of the Montpellier project in the background.

The Lizmap Web Client application error log says: 2020-12-24 16:32:27 xxx.xxx.236.209 error 2020-12-24 16:32:27 [403] unzulässige Anfrage(ERROR: current transaction is aborted, commands ignored until end of transaction block(SELECT "ug"."login", "ug"."id_aclgrp" FROM "jacl2_user_group" AS "ug" WHERE "ug"."login" = 'admin')) /var/www/lizmap-web-client-3.4.0/lib/jelix/plugins/db/pgsql/pgsql.dbconnection.php 180

I checked the lizmap PostgreSQL database and all the tables are there and the user exists. The query executed in DBeaver returns the correct login and id_aclgrp.

This is a updated version of the issue from last august #1789

Lizmap 3.4.0 QGIS Lizmap-Plugin 3.3.3 QGIS Desktop 3.10.9-A Coruña QGIS FCGI server 3.10.12-A Coruña PostgreSQL 12.5 PostGIS 3.1 Ubuntu 18.04.3: OS (MacOS): Browser (Firefox, Chrome):