I advise you read our dedicated page at https://docs.centreon.com/docs/migrate/migrate-from-3-4/

You would install a new server (e.g. on Alma Linux 8 or 9) then follow the procedure.

Thanks, rchauvel. I did use that article. I installed new then synced database and directories. what i can not find in it is, Do i have to do anything in my poller servers? do i have to migrate them also? or they will work with my upgraded central engine. 

Yes you do need to migrate your pollers too. Please follow instructions at https://docs.centreon.com/docs/migrate/migrate-from-el-to-el/#migrating-a-poller

Thanks, You guys are the best! If i migrating pollers then i only have to install new pollers right? above link says to install and synchronize. as a first step can you tell me do i have to install new pollers and sync directories or what should i do 

@rchauvel  I am confused for the migration of poller servers. I have two poller servers. What should i do first?

1. Install fresh pollers in new server and register to new server?
2. Or Install new pollers then rsync data with older poller and re register it?

As a first step what should i do. I am not able to get it from the migrate poller document it says 
 

1. On the central server, go to Configuration > Pollers. Select the poller that was migrated and update its IP address (if it has changed).

how can i update ip poller is not migrated yet and i chang ip how ill i get the data of pollers?

It’s confusing. Really appericiate your help if you can guide me here 

Thanks in advance 

Sorry for this. We’ll get the doc updated for more clarity.

You only need to rsync if you have custom plugins. If it is all standard, then the fresh install will be enough.

Okay great, So new pollers will do the polling with all data right no need to change anything in end user device?

yes, correct, rsync with old pollers if you have custom plugins

So basically, We only need to migrate central and setup new pollers and update poller’s ip correct? 

yes

These are my pollers configurations, After upgrade this is my poller configuration still not installed new pollers for 10.0.4.7 and 8 but the local central one supposed to work why it is showing offline?

Why do you say it is off line? It shows Running=Yes. Maybe you need to re-export the config since this is a big step from 2.8?

i don't think it's running just showing after restoring the database its just showing it's running.  even when I added new poller it's not running either. I don’t know if its with the poller or the central configuration. This is what i get when i export configuration of a poller engine : log started
Reading main configuration file '/var/cache/centreon/config/engine/2/centengine.DEBUG'.
Reading resource file '/var/cache/centreon/config/engine/2/resource.cfg'
Warning Host 'Reveb_-_SYNO' has no services associated with it!
Warning Host 'ITK_-_CDC' has no services associated with it!
Warning Host 'Reveb_-_SYNO2' has no services associated with it!
Checking global event handlers...
Checking obsessive compulsive processor commands...

Checked 77 commands.
Checked 0 connectors.
Checked 6 contacts.
Checked 0 host dependencies.
Checked 80 host escalations.
Checked 4 host groups.
Checked 197 hosts.
Checked 0 service dependencies.
Checked 0 service escalations.
Checked 3 service groups.
Checked 2858 services.
Checked 8 time periods.
Total Warnings: 3
Total Errors: 0

Have you checked this? 

yes but when i checked this in new poller it gave me this,


[root@localhost]# tail -f /var/log/centreon-gorgone/gorgoned.log
2023-08-31 10:15:54 - ERROR - no such table: gorgone_information
2023-08-31 10:15:55 - ERROR - no such table: gorgone_information
2023-08-31 10:15:55 - ERROR - no such table: gorgone_identity
2023-08-31 10:15:56 - ERROR - no such table: gorgone_identity