Unable to install via composer

[kobuki]

Trying to install on RC 1.4.10:

# composer require roundcube/elastic4mobile
Do not run Composer as root/super user! See https://getcomposer.org/root for details


  [InvalidArgumentException]
  Could not find a matching version of package roundcube/elastic4mobile. Check the package spelling, your version constraint and that the package is available in a stability which matches your minimum-stability (sta
  ble).

[daniel712]

Same here:
Unable to install on RC 1.6.1.

Could not find a version of package roundcube/elastic4mobile matching your minimum-stability (stable). Require it with an explicit version constraint allowing its desired stability.

Thanks for info!
Daniel

[kochs-online]

This error messages indicates that there is no stable version of this plugin found by Composer. You can install the latest unstable version using this command:

composer require roundcube/elastic4mobile:dev-master

Props to Stack Overflow user Bizley for this answer.