A feature with ID X has already been installed in this farm. Use the force attribute to explicitly re-install the feature.

SYMPTOMS:

While deploying or upgrading a Bamboo product, the installation is partially successful, but one of the WSP files (solutions) does not deploy onto one of the servers in the farm.  The feedback in the Bamboo installer or in Central Administration's Solution Management page shows:

      "A feature with ID X has already been installed in this farm. Use the force attribute to explicitly re-install the feature.

Or the following error displays:

CAUSE:

   This error indicates that the product's site collection feature(s) were not deactivated and removed when the solution was undeployed and uninstalled from the farm.
While it would likely be possible to install the solution as recommended in the feedback using the -force parameter, this is not recommended.

If the feature activates a content type, and the feature is not deactivated and removed before the solution is deployed, then the content type can remain in the farm in a disassociated state.

That is, you will be able to activate or deactivate the feature, but the content type will not appear where needed, and the product may not perform as expected.

RESOLUTION:

1. Install and run the CodePlex Feature Admin Manager tool, and use it to find the Bamboo Lookup Plus site collection feature.

   http://featureadmin.codeplex.com/

2. Go through each site collection on each web application, and check the list of features.  When you see the feature that is referenced in the error, remove it.

3. Attempt to deploy the solution again.  It should deploy with no errors.