Please follow this upgrade guide only if you installed Agents for Linux using Resilio package repository. This instruction implies you already created Resilio repository file as well as registered PGP key, therefore it won't work if you installed Agent by other means.
The upgrade utilizes DEB or RPM package manager and only implies adding a new repository, containing 2.4 packages.
For Debian-based Linux (Debian, Ubuntu, Zorin, Elementary)
Add the following line to file /etc/apt/sources.list.d/resilio-agent.list:
deb http://linux-packages.resilio.com/resilio-agent-2.4/deb resilio-agent non-free
Update your repository and upgrade the agent:
sudo apt-get update
sudo apt-get install --only-upgrade resilio-agent
For RPM-based Linux
Add the following lines to file /etc/yum.repos.d/resilio-agent.repo to register 2.4 Resilio repository:
name=Resilio Agent $basearch
sudo yum update resilio-agent