Sorry for my english, i'm using a translator
Good afternoon, I have the following problem, running zabbix in a virtual environment (vmware) in Ubuntu 21.10, only in my case I did an update from 5.0 to 5.4 and it throws me the error when entering the dashboard:

I do a telnet to the local host but I get the following:
[root@zabbix-server]# telnet localhost 10051
Trying 127.0.0.1...
telnet: connect to address 127.0.0.1: Connection refused
[root@zabbix-server]#
But if I do it to 10050 this comes out:
[root@zabbix-server]# telnet localhost 10050
Trying 127.0.0.1...
Connected to local host.
Escape character is '^]'.
Connection closed by foreign host.
[root@zabbix-server]#
I followed the instructions in the following url:
After installing the new repository I get the following error:
*Unable to establish SSL connection.
I run the following command:
*Unable to establish SSL connection.
I continue with the steps below, and the error appears

This error is because in the zabbix_server.conf file there was no database password, I put the password and restart the zabbix-server service and everything normal, update the database, I enter the dashboard and that's when the error appears from image 1
**I did the same upgrade procedure on another server ubuntu 20.04 and there were no problems when entering the dashboard**
Good afternoon, I have the following problem, running zabbix in a virtual environment (vmware) in Ubuntu 21.10, only in my case I did an update from 5.0 to 5.4 and it throws me the error when entering the dashboard:
I do a telnet to the local host but I get the following:
[root@zabbix-server]# telnet localhost 10051
Trying 127.0.0.1...
telnet: connect to address 127.0.0.1: Connection refused
[root@zabbix-server]#
But if I do it to 10050 this comes out:
[root@zabbix-server]# telnet localhost 10050
Trying 127.0.0.1...
Connected to local host.
Escape character is '^]'.
Connection closed by foreign host.
[root@zabbix-server]#
I followed the instructions in the following url:
After installing the new repository I get the following error:
*Unable to establish SSL connection.
I run the following command:
*Unable to establish SSL connection.
I continue with the steps below, and the error appears
This error is because in the zabbix_server.conf file there was no database password, I put the password and restart the zabbix-server service and everything normal, update the database, I enter the dashboard and that's when the error appears from image 1
**I did the same upgrade procedure on another server ubuntu 20.04 and there were no problems when entering the dashboard**