The error seems to occur during the download of thirtybees-v1.0.7.zip to the autoupgrade/download folder. The archive thirtybees-extra-v1.0.7.zip is correctly downloaded (together with thirtybees-file-actions-v1.0.7.json). Since the migration process seems to delete the contents of the autoupgrade/download folder before attempting to download the archives, it's useless to manually place them before launching the migration.