The documentation page EXPORTERS/&AMP;NUM;OPTIMUM.EXPORTERS.TASKSMANAGER.CREATE_REGISTER.BACKEND doesn’t exist in v1.21.2, but exists on the main version. Click <a href="/docs/optimum/main/en/exporters/&amp;num;optimum.exporters.TasksManager.create_register.backend">here</a> to redirect to the main version of the documentation.