I’ve been writing migration code for my wife’s WordPress blog to Drupal 8, using the migrate framework. This framework attempts to track if a particular migration is currently running, but does not always unset that flag if it crashed with a PHP fatal error (which will happen when you are writing new code.) Subsequent attempts to run the migration will produce “Migration your_migration_name is busy with another operation: Importing”.
To unstick it in this case, you can run the following in drush:
drush php-eval 'var_dump(Drupal::keyValue("migrate_status")->set('your_migration_name', 0))'
You have your quotes wrong here. The example you’ve given will result in a syntax error. This will work:
drush php-eval “var_dump(Drupal::keyValue(‘migrate_status’)->set(‘your_migration_name’, 0));”
Also just pointing out that in my previous comment, the “normal” single quotes have been replaced by “special” single quotes automatically, so copying/pasting this will not work and you will need to replace them again with “normal” single quotes.