Recently we released a change which doesn’t allow to use : (colon) any more when updating the Project Key. However you are right, when using sonar plugin on Maven or Gradle, the auto generated project key contains a colon and we are aware of this edge case. You are still able to update the Project Key, if you replace the colon with a - (dash) for example. Hopefully this solution will work for you and sorry for this inconvenience.
Important query, is this change permanent or is it temporary? I have to make the change to 370 projects, in SonarCloud and in the code of the devops pipelines. Please, I would like you to confirm if it is a change forever, before starting my adaptations.
This is a breaking change that has a wide range implications for projects and governance including permission templates and auxiliary tooling! We are managing several hundred projects within SonarCloud and were hit by this change without any notice or potential workaround.