Zabbix Upgarde 3.4.15 to 6.0.8

[Jo09]

Hello,

We are planning to upgrade Zabbix from 3.4.15 to 6.0.8.
Is there any way to keep historical data, graphs etc? (Export/Import?)

Thank you

[cyber]

Prepare your 6.0 environment (new OS, fresh versions of everything etc...). Don't start it ... Transfer your DB to new platform (new db version but old schema with data). When you first time start your new version, it should connect to DB and do all the necessary conversions/updates etc. That is the short version...
Long version involves a lot of reading of all the release notes of inbetween versions, making sure you do some other needed conversions like charsets and primary keys etc... This is not an easy task an d probably will take several attempts from you.