Thanks for your question and welcome to the forums!
Unfortunately, you can’t specify all projects with the promote-release command. The promote-release command expects one project name to be provided with the --project switch.
There are a few options for what you are trying to accomplish.
One option would be to script this call and use a loop to call the command for each project. You can hard code the project list or use something like octo.exe’s list-projects command to get a list of projects and iterate through that. You can use the Octopus REST API to find the list of projects. If you go this route, you’d want to remove the --progress option as that would wait for the command to finish one deployment before the next one begins.
Another option would be to use the Deploy a Release step built-in to Octopus. In this case, you would have one project that has a step for each of the other projects that should be deployed. You can use a single deployment of that project to trigger deployments in all of the other projects.
Let me know if you have any other questions or need more information on those options.