Drush 11.6.0
The processItem() expects an array to be passed for the context, but it fails when a DrushBatchContext is used instead. If I switch the type to \DrushBatchContextthen it works correctly.
drush footnotes:upgrade-3-to-4 node
> [error] TypeError: Drupal\footnotes\Upgrade\FootnotesUpgradeBatchManager::processItem(): Argument #5 ($context) must be of type array, DrushBatchContext given, called in /var/www/vendor/drush/drush/includes/batch.inc on line 256 in Drupal\footnotes\Upgrade\FootnotesUpgradeBatchManager::processItem() (line 28 of /var/www/docroot/modules/contrib/footnotes/src/Upgrade/FootnotesUpgradeBatchManager.php) #0 /var/www/vendor/drush/drush/includes/batch.inc(256): Drupal\footnotes\Upgrade\FootnotesUpgradeBatchManager::processItem('node', 2, Array, Array, Object(DrushBatchContext))
> #1 /var/www/vendor/drush/drush/includes/batch.inc(201): _drush_batch_worker()
> #2 /var/www/vendor/drush/drush/includes/batch.inc(95): _drush_batch_command('5')
> #3 /var/www/vendor/drush/drush/src/Drupal/Commands/core/BatchCommands.php(20): drush_batch_command('5')
> #4 [internal function]: Drush\Drupal\Commands\core\BatchCommands->process('5', Array)
> #5 /var/www/vendor/consolidation/annotated-command/src/CommandProcessor.php(276): call_user_func_array(Array, Array)
> #6 /var/www/vendor/consolidation/annotated-command/src/CommandProcessor.php(212): Consolidation\AnnotatedCommand\CommandProcessor->runCommandCallback(Array, Object(Consolidation\AnnotatedCommand\CommandData))
> #7 /var/www/vendor/consolidation/annotated-command/src/CommandProcessor.php(176): Consolidation\AnnotatedCommand\CommandProcessor->validateRunAndAlter(Array, Array, Object(Consolidation\AnnotatedCommand\CommandData))
> #8 /var/www/vendor/consolidation/annotated-command/src/AnnotatedCommand.php(391): Consolidation\AnnotatedCommand\CommandProcessor->process(Object(Symfony\Component\Console\Output\ConsoleOutput), Array, Array, Object(Consolidation\AnnotatedCommand\CommandData))
> #9 /var/www/vendor/symfony/console/Command/Command.php(326): Consolidation\AnnotatedCommand\AnnotatedCommand->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
> #10 /var/www/vendor/symfony/console/Application.php(1081): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
> #11 /var/www/vendor/symfony/console/Application.php(320): Symfony\Component\Console\Application->doRunCommand(Object(Consolidation\AnnotatedCommand\AnnotatedCommand), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
> #12 /var/www/vendor/symfony/console/Application.php(174): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
> #13 /var/www/vendor/drush/drush/src/Runtime/Runtime.php(124): Symfony\Component\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
> #14 /var/www/vendor/drush/drush/src/Runtime/Runtime.php(51): Drush\Runtime\Runtime->doRun(Array, Object(Symfony\Component\Console\Output\ConsoleOutput))
> #15 /var/www/vendor/drush/drush/drush.php(79): Drush\Runtime\Runtime->run(Array)
> #16 /var/www/vendor/drush/drush/drush(4): require('/var/www/vendor...')
> #17 /var/www/vendor/bin/drush(119): include('/var/www/vendor...')
> #18 {main}.