How to force a running migration to stop I created a migration with a query that seems to have broken my migration. I added two groupBy on a query, instead of two orderBys. As a result, running drush mi MyMigration got stuck in what appeared to be an endless loop.

I CTRL-C'd the process and then ran a drush mst --all, but now the status is reporting as "Stopping" in the UI, and the drush ms command does not return.

I tried stoping and restarting MAMP, but to no effect.

Is there someway to force my migration to get unstuck?
Did you try migrate-reset-status, and possibly with --force:
https://www.drupal.org/node/1561820

Otherwise I typically restart PHP manually once (restart your webserver) and then use Drush to rollback all the migrations to try again fresh.

EDIT

I rarely use the UI as everything is usable and scriptable via drush when using Migrate. And trying to use a webserver to check the status of long-running tasks can be error-prone.