Dear Igor,
Thank you for contacting Zabbix.
From the perspective of the Zabbix application (component "zabbix-server"), I'm unable to locate the error message "Unable to read the database instance ID".

Could it be possible that the line starts with "query failed" and contains the error above? Please share more original lines from zabbix_server.log.

Please simulate if the dedicated application user can read the data.

Observe the connection characteristics to communicate with DB:

grep ^DB /etc/zabbix/zabbix_server.conf

From the same host where service "zabbix-server" is installed, use "mysql" client utility to connect to the database. Use dedicated user from the previous output:

mysql --host=dns.of.ip --user=zabbix --password='zabbix' --database=zabbix

See how many items are inside:

SELECT COUNT(*) FROM items;

A few recognizable host titles which did exist in old instances:

SELECT hosts.host FROM hosts WHERE hosts.flags IN (0,4) AND hosts.status IN (0,1);

Does the SELinux run on the host? This will tell:

getenforce

Hi Aigars. Thank you for your reply. 

Follow the commands and images. 

I've changed this query to COUNT because of privacy policies. 

SELECT hosts.host FROM hosts WHERE hosts.flags IN (0,4) AND hosts.status IN (0,1);

DB configuration on zabbix_server.conf: 

SELECT COUNT(*) FROM items;

SELECT COUNT(*) FROM hosts WHERE hosts.flags IN (0,4) AND hosts.status IN (0,1);

Selinux configuration:

Sorry, the message is "cannot read instance id" not "unable". 
See log file lines:
 49052:20240104:174819.899 Starting Zabbix Server. Zabbix 6.0.23 (revision 315e9acac58).
 49052:20240104:174819.899 ****** Enabled features ******
 49052:20240104:174819.899 SNMP monitoring:           YES
 49052:20240104:174819.899 IPMI monitoring:           YES
 49052:20240104:174819.899 Web monitoring:            YES
 49052:20240104:174819.899 VMware monitoring:         YES
 49052:20240104:174819.899 SMTP authentication:       YES
 49052:20240104:174819.899 ODBC:                      YES
 49052:20240104:174819.899 SSH support:               YES
 49052:20240104:174819.899 IPv6 support:              YES
 49052:20240104:174819.899 TLS support:               YES
 49052:20240104:174819.899 ******************************
 49052:20240104:174819.900 using configuration file: /etc/zabbix/zabbix_server.conf
 49052:20240104:174819.932 current database version (mandatory/optional): 00600000/06000043
 49052:20240104:174819.933 required mandatory version: 06000000
 49052:20240104:174819.952 cannot read instance id from database

I've noted that config table isn't populated as well: 

Hi Igor. Sorry for late reply.

There should be only one row in the config table and you have this one row. It seems the column "instanceid" currently has an empty value.

The syntax of instanced is a 32-character long hex string. We can use a bash command to generate one:

< /dev/urandom tr -dc a-f0-9 | head -c${1:-32};echo;

It can print a string like: "cafc344fe615d8cb24a416cdbd3e9201"

After that, you can use DB command to update the field:

UPDATE config SET instanceid='cafc344fe615d8cb24a416cdbd3e9201';

Please check if other data is there. There should be a lot:

SELECT * FROM config;

At the bare minimum via stock installation, we have:

INSERT INTO `config` (`configid`,`work_period`,`alert_usrgrpid`,`discovery_groupid`,`dbversion_status`,`geomaps_tile_provider`) values ('1','1-5,09:00-18:00','7','5','','OpenStreetMap.Mapnik');

Hello, Aigars! 

Thank you for your help. 

The problem was in AWS tool.
The DMS was getting timeout during data migration, which caused data loss in target database. 

It's ok now. 

Thank you.