Hi, you need to use the version in the release section, not the source from the master branch itself. That version is unstable at best, as it contains code related to a rebuild.
Edit: also remember, pockethold is an 3rd party solution, and not directly connected to the flarum project. If you are migrating an existing community, I highly recommend you use the official installation method. That way it will be easier to get support for your migration.