Under specific circumstances, the following error is generated on www.example.com/package/install/<package_name> when trying to install a package:

The requested page could not be displayed. (3)

The requested object is not available.

Possible reasons:
* The ID number of the object is incorrect. Check the URL for spelling mistakes.
* The object is no longer available.

Steps to reproduce:

1. On the admin interface, import an existing package (say, "package_1");
2. Click on "Install package - but don't actually install;
3. Instead, go back to the main package page (www.example.com/package/list);
4. Now remove the package you were just trying to install previously in step 2;
5. Import another package (say, "package_2");
6. Error.