Drush 9 - Destination Argument Does Not Exist I've been struggling a lot with Drush 9 sql:sync the past few months. I've gotten it to work a few times, but I've been stumped by this most recent problem:

$ drush sql:sync @prodv2 @local --debug 
Using the Drush script found at /Applications/MAMP/htdocs/ianmoffitt/vendor/drush/drush/drush using proc_open
 [preflight] Config paths: /Applications/MAMP/htdocs/ianmoffitt/vendor/drush/drush/drush.yml,/Applications/MAMP/htdocs/ianmoffitt/drush/drush.yml
 [preflight] Alias paths: /Applications/MAMP/htdocs/ianmoffitt/web/drush/sites,/Applications/MAMP/htdocs/ianmoffitt/drush/sites
 [preflight] Commandfile search paths: /Applications/MAMP/htdocs/ianmoffitt/vendor/drush/drush/src,/Applications/MAMP/htdocs/ianmoffitt/drush
 [bootstrap] Bootstrap to none [0.13 sec, 8.14 MB]
 [bootstrap] Drush bootstrap phase 0 [0.13 sec, 8.14 MB]
 [bootstrap] Try to validate bootstrap phase 0 [0.13 sec, 8.14 MB]
 [error]  The "destination" argument does not exist. [0.13 sec, 8.19 MB] 

Can't find anything online towards this specific error message. Not sure what I'm missing or what to even check.

Again, this command worked about a week or so ago. All I've done since then is run composer update. Did something change recently?

Using Drush 9.3.0.
Just for the record - in my case, given "destination" argument was coming from an outdated custom Policy command I got when I was setting up the project - https://github.com/drupal-composer/drupal-project/blob/8.x/drush/Commands/PolicyCommands.php

It should be "target" instead and the current state of https://github.com/drupal-composer/drupal-project reflects that change.