Read the upgrade notes from the new Zabbix version you want to install.

What was that? Yes, before performing any upgrades, take a little time, go to the Zabbix manual, and read the upgrade notes. If you're jumping over a few major versions, do read all of the upgrade notes in between. Even if you've followed Zabbix development a bit, you might've missed some change that could cause problems; removed or added configuration parameters, memory requirement changes, or API changes; the upgrade notes should list all significant changes.

It's also highly suggested to read the pages on new features and improvements, called What's new. While it's much less risky to miss some of those changes, knowing about them could help you use Zabbix in a more efficient way.

Let's talk about the upgrade process itself now. This process and compatibility will differ depending on the version change you're performing:

• A minor version upgrade inside the same major version is simple and easy to undo
• A major version upgrade is more complicated, and hard or impossible to undo