Upgrade 2.3.8 to 2.4.12

running Debian 9
I upgraded manually downloading 2.4.12 over 2.3.8 with dpkg -i …

when I run:
urbackupsrv run -v debug

I get:
2020-06-07 10:37:04: Starting HTTP-Server on port 55414
2020-06-07 10:37:04: HTTP: Server started up successfully!
2020-06-07 10:37:04: SQLite: recovered 14076 frames from WAL file /var/urbackup/backup_server.db-wal code: 283
2020-06-07 10:37:04: SQLite: recovered 26 frames from WAL file /var/urbackup/backup_server_link_journal.db-wal code: 283
2020-06-07 10:37:04: SQLite: recovered 189 frames from WAL file /var/urbackup/backup_server_settings.db-wal code: 283
2020-06-07 10:37:04: SQLite: recovered 14076 frames from WAL file /var/urbackup/backup_server.db-wal code: 283
2020-06-07 10:37:04: SQLite: recovered 189 frames from WAL file /var/urbackup/backup_server_settings.db-wal code: 283
2020-06-07 10:37:04: SQLite: recovered 26 frames from WAL file /var/urbackup/backup_server_link_journal.db-wal code: 283
2020-06-07 10:37:04: Started UrBackup…
MOUNT TEST OK
2020-06-07 10:37:04: Testing if backup destination can handle subvolumes and snapshots…
Testing for btrfs…
Create subvolume ‘/urbackup/testA54hj5luZtlorr494/A’
Create a snapshot of ‘/urbackup/testA54hj5luZtlorr494/A’ in ‘/urbackup/testA54hj5luZtlorr494/B’
Delete subvolume (commit): ‘/urbackup/testA54hj5luZtlorr494/A’
Delete subvolume (commit): ‘/urbackup/testA54hj5luZtlorr494/B’
BTRFS TEST OK
2020-06-07 10:37:05: Backup destination does handle subvolumes and snapshots. Snapshots enabled for image and file backups.
2020-06-07 10:37:05: Testing if backup destination can handle filesystem transactions…
2020-06-07 10:37:05: Testing for hardlinks in backup destination…
2020-06-07 10:37:05: Could create hardlink at backup destination. Hardlinks enabled.
2020-06-07 10:37:05: Testing for reflinks in backup destination…
2020-06-07 10:37:05: Could create reflink at backup destination. Reflinks enabled.
2020-06-07 10:37:05: InternetService: Server started up successfully!
Segmentation fault

The server runs very well on 2.3.8 and if i downgrade to 2.3.8 over 2.4.12 things work perfectly again.

I also tried going to 2.4.9 and I get the same results

Do you need any more logs or info?

Thanks for your help

On 2.3.8 if I run it manually:
urbackupsrv run -v debug

I get:
2020-06-07 10:43:47: Starting HTTP-Server on port 55414
2020-06-07 10:43:47: HTTP: Server started up successfully!
2020-06-07 10:43:47: SQLite: recovered 14076 frames from WAL file /var/urbackup/backup_server.db-wal code: 283
2020-06-07 10:43:47: SQLite: recovered 28 frames from WAL file /var/urbackup/backup_server_link_journal.db-wal code: 283
2020-06-07 10:43:47: SQLite: recovered 193 frames from WAL file /var/urbackup/backup_server_settings.db-wal code: 283
2020-06-07 10:43:47: SQLite: recovered 14076 frames from WAL file /var/urbackup/backup_server.db-wal code: 283
2020-06-07 10:43:47: SQLite: recovered 193 frames from WAL file /var/urbackup/backup_server_settings.db-wal code: 283
2020-06-07 10:43:47: SQLite: recovered 28 frames from WAL file /var/urbackup/backup_server_link_journal.db-wal code: 283
2020-06-07 10:43:47: Started UrBackup…
MOUNT TEST OK
2020-06-07 10:43:47: Testing if backup destination can handle subvolumes and snapshots…
Testing for btrfs…
Create subvolume ‘/urbackup/testA54hj5luZtlorr494/A’
Create a snapshot of ‘/urbackup/testA54hj5luZtlorr494/A’ in ‘/urbackup/testA54hj5luZtlorr494/B’
Delete subvolume (commit): ‘/urbackup/testA54hj5luZtlorr494/A’
Delete subvolume (commit): ‘/urbackup/testA54hj5luZtlorr494/B’
BTRFS TEST OK
2020-06-07 10:43:47: Backup destination does handle subvolumes and snapshots. Snapshots enabled for image and file backups.
2020-06-07 10:43:47: Testing if backup destination can handle filesystem transactions…
2020-06-07 10:43:47: Testing for hardlinks in backup destination…
2020-06-07 10:43:47: Could create hardlink at backup destination. Hardlinks enabled.
2020-06-07 10:43:47: Testing for reflinks in backup destination…
2020-06-07 10:43:47: Could create reflink at backup destination. Reflinks enabled.
2020-06-07 10:43:47: Binding to interface eno3 for broadcasting…
2020-06-07 10:43:47: Broadcasting on interface IP 54.39.19.136
2020-06-07 10:43:47: InternetService: Server started up successfully!
2020-06-07 10:43:47: UrBackup Server start up complete.
2020-06-07 10:43:47: Server started up successfully!
2020-06-07 10:43:47: Looking for old Sessions… 0 sessions
2020-06-07 10:43:47: Downloading version file…
2020-06-07 10:43:48: Downloading version file…
2020-06-07 10:43:48: Downloading version file…
2020-06-07 10:43:48: Downloading server version info…
2020-06-07 10:43:48: Downloading dataplan database…
2020-06-07 10:46:13: InternetService: No available slots… starting new Worker

I figured it out:

In config file /etc/default/urbackupsrv

I had:
BROADCAST_INTERFACES=""
because I did NOT want to broadcast the server

when I set like this:
BROADCAST_INTERFACES=“lo”

Everything worked.