How to upgrade a Discourse site from beta to stable release?

There are 4 branches of Discourse: master, tests-passed, beta and stable. All Discourse sites by default and docker installed Discourse sites run the tests-passed branch.

Moving to the stable version:
Before doing this, don’t forget to back up your Discourse. Also, if you are using Cloudflare or any other CDN, change your site settings to development mode.

To find out which version your Discourse site uses, go to:
cd /var/discourse/containers
nano app.yml

In the app.yml, find the following line:
## Which Git revision should this container use? (default: tests-passed)
#version: tests-passed

Uncomment that version: test-passed line and then change tests-passed to stable as follows.

## Which Git revision should this container use? (default: tests-passed)
version: stable

Save and exit the app.yml file.

Next, run:
cd /var/discourse
git pull
./launcher rebuild app
Once this is done, your Discourse site will run on a stable build.

Note:
These instructions are for docker installed Discourse.
Assumes your YAML configuration file is called “app.yml”.
The site will be offline for up to 10 minutes while it is rebuilding.