Failed to call grubby to list available boot entries

Leapp 是一款就地升级工具，与传统的再部署项目相比，该工具能帮助您以更少的时间和精力获得最新的版本，简化您升级红帽企业 Linux 环境的方式。 Leapp 旨在帮助降低红帽企业 Linux 主要版本的升级风险，该工具还可以在升级开始和结束时减少系统管理员的工作范围，同时降低操作系统版本控制的难度。
Leapp 的升级前分析功能有助于确保应用的兼容性并修复所有问题。 Leapp会自动突出显示潜在的不兼容性，甚至会建议如何修复兼容性错误，比如应该如何重新配置应用或安装哪个硬件驱动程序。然后， Leapp 可以在几分钟内执行就地升级，减少停机时间和延迟，同时保留您的自定义、配置和首选项。 Leapp 支持从红帽企业 Linux 7 升级到 8，以及从红帽企业 Linux 8 升级到 9。 Failed to call <code>grubby</code> to list available boot entries
借助 Leapp，您可以获得简化升级所需的控制权、信心和自由度，并开始充分利用红帽企业 Linux 9 所提供的所有功能。 Leapp 是一款自助实用程序，您可以自行使用。
近期我们在使用leapp来将操作系统RedHat Enterprise Linux 7.1升级到Red Hat Enterprise Linux 8.4的时候，出现了如下错误：

Risk Factor: high
Title: Failed to call `grubby` to list available boot entries.
Summary: {"details": "Command ['grubby', '--info', 'ALL'] failed with exit code 1.", "stderr": "Process Process-204:\nTraceback (most recent call last):\n  File \"/usr/lib64/python2.7/multiprocessing/process.py\", line 258, in _bootstrap\n    self.run()\n  File \"/usr/lib64/python2.7/multiprocessing/process.py\", line 114, in run\n    self._target(*self._args, **self._kwargs)\n  File \"/usr/lib/python2.7/site-packages/leapp/repository/actor_definition.py\", line 72, in _do_run\n    actor_instance.run(*args, **kwargs)\n  File \"/usr/lib/python2.7/site-packages/leapp/actors/__init__.py\", line 289, in run\n    self.process(*args)\n  File \"/usr/share/leapp-repository/repositories/system_upgrade/el7toel8/actors/sourcebootloaderscanner/actor.py\", line 18, in process\n    scan_source_boot_loader_configuration()\n  File \"/usr/share/leapp-repository/repositories/system_upgrade/el7toel8/actors/sourcebootloaderscanner/libraries/sourcebootloaderscanner.py\", line 87, in scan_source_boot_loader_configuration\n    entries=scan_boot_entries()\n  File \"/usr/share/leapp-repository/repositories/system_upgrade/el7toel8/actors/sourcebootloaderscanner/libraries/sourcebootloaderscanner.py\", line 41, in scan_boot_entries\n    grubby_output = run(CMD_GRUBBY_INFO_ALL, split=True)\n  File \"/usr/lib/python2.7/site-packages/leapp/libraries/stdlib/__init__.py\", line 181, in run\n    stdin=stdin, env=env, encoding=encoding)\n  File \"/usr/lib/python2.7/site-packages/leapp/libraries/stdlib/call.py\", line 217, in _call\n    os.execvpe(command[0], command, env=environ)\n  File \"/usr/lib64/python2.7/os.py\", line 353, in execvpe\n    _execvpe(file, args, env)\n  File \"/usr/lib64/python2.7/os.py\", line 380, in _execvpe\n    func(fullname, *argrest)\nOSError: [Errno 2] No such file or directory\n"}