And it worked just fine, except for one thing : The users.
The users are not migrated, which may be fine, but I can’t see any way to migrate users in the official documentation.
How can I migrate users from my local instance to Gitlab.com ?
My second trouble is that I have some users with a particular ID and those IDs match existing users on Gitlab.com. So, if I migrate my user, I’ll have to change their ID and then when I’ll migrate my project all issues and mentions will be linked to the wrong user.
Is there a way to deal with conflict in user ID ?
Those troubles are really preventing me to migrate my GitLab project.
As far as I can see, you will not be able to migrate users. You would have to get them to register on the public gitlab.com instance and then you would have to manually add them into your projects once they have registered. Considering the fact also that there can be username conflicts - eg: someone is already registered with that login name or email address, then there isn’t really something you can do about it. This is why you won’t be able to migrate users to an instance that you are not an administrator of.
You could only migrate the entire server including users, to an instance of which you have complete control over by using the backup/restore procedures for example moving from your existing onsite server to a new onsite server. But that will not apply to a public instance like gitlab.com.