A Word of Warning - Removing Default External Language Server Settings

Hi everyone!

If you are working with IRIS 2021+ and you remove all of the built in entries for External Language Servers, there is an unexpected consequence that may prevent you from running an installer to upgrade your version of IRIS. This does appear to be a bug which has been raised with WRC, however there are some people that may have recently removed these settings and then will soon be upgrading their environment and could face this same issue.

Specifically, the removal of all the External Language Server entries will also remove the "[Gateways]" heading in the iris.cpf file, and this being missing will then cause the validation ran by the installer (##Class(Config.CPF).Validate()) to fail, preventing the installer from running the upgrade.

There are two workarounds:

1. Manually add the heading into iris.cpf before running the upgrade (bit fiddly if you're not sure where it was in the file before)
2. Add a single External Language Server entry back into the system prior to upgrading.

I would be surprised if this remained an issue for too long, but I suspect there is a subset of users that could be going through this soon that could get caught out like I was.