Upgrade Precautions

Only the upgrade from an earlier version to a later version is supported. For example, version 2.0.4 can be upgraded to version 3.0.RC1, but version 3.0.RC1 cannot be upgraded to version 2.0.4.
Version 2.0.4 incorporates earlier versions and can only be directly upgraded to 3.0.RC1 or later.

The haveged dependency must be installed before the upgrade. Otherwise, the upgrade will fail. The installation command is as follows.
- For Ubuntu, Linx 6.0.90, Linx 6.0.100, or UOS 20, run the following command:
```
apt install haveged
```
- For EulerOS or CentOS 7.6, run the following command:
```
yum install haveged
```
After haveged is installed, run the following commands to start the haveged service:
```
systemctl enable haveged
systemctl start haveged
```
Before the upgrade, run the following commands to install the dataclasses dependency:
```
pip3 install dataclasses
```
If the Python version is 3.6, you need to manually install dataclasses. If the Python version is 3.7, you do not need to manually install dataclasses.

Parent topic: Preparations