If you don't use a CLA, AND you want to change the outbound license for a project, AND you have used a copyleft license (like GPL, AGPL, or LGPL) you usually have to do a clean-up project to get new rights for your project. That is a pain!
When I have advised on those projects, we usually did a 3-tier approach. Some contributions are very small (a few lines, a non-code change) and don't usually require any re-licensing. Some contributions are from contributors who are still involved in the project, and we just send them a CLA to acknowledge. (Usually they don't object.) For those who don't respond, you can push out a notice saying "We are changing our project license, please speak now or forever hold your peace." That is not the best position, legally, but it's often all you can do. If anyone actually does object, you remove the code from the project.
If you have used a permissive license for the project, you don't need all this. You just preserve the original license notice for pre-change contributions. You end up with two license notices, but that's not such a bad thing.
If you don't use a CLA, AND you want to change the outbound license for a project, AND you have used a copyleft license (like GPL, AGPL, or LGPL) you usually have to do a clean-up project to get new rights for your project. That is a pain!
When I have advised on those projects, we usually did a 3-tier approach. Some contributions are very small (a few lines, a non-code change) and don't usually require any re-licensing. Some contributions are from contributors who are still involved in the project, and we just send them a CLA to acknowledge. (Usually they don't object.) For those who don't respond, you can push out a notice saying "We are changing our project license, please speak now or forever hold your peace." That is not the best position, legally, but it's often all you can do. If anyone actually does object, you remove the code from the project.
If you have used a permissive license for the project, you don't need all this. You just preserve the original license notice for pre-change contributions. You end up with two license notices, but that's not such a bad thing.
Thanks for the question!
I guess "tell me the license you go with and I'll tell you who you are" talks a lot about me, or the friends I hang out with? š
Thank you for the answers to both questions! I now know a lot more about this than I did before.