"Cannot debug project unless a host..." what?

Most likely it's because the component project is still loaded. Close the package project, then reopen the application project is necessary.

May be you have opened with IDE not a project, but a Component's code and try to run it ? You need to close the Component's code and open a Project, then you could compile, build and run it ....

seems like you are trying to debug a DLL... that's the only case where I have seen that error, and the solution is just as the message suggests... to add the Run|Parameters to specify the host application

No actually, if I have a project open and I'm trying to add additional components (recompile the package) I get the error... no clue still

May be you forgot to add the path of the installed new Components into:
 -  DELPHI IDE Menu "Tools"
    - Menu Item "Environment Options"
      - Tab "Library"
         - "Library Path" Button with caption "..."
           - Write Into the Edit Component the full path to  the installed new Components
             - Press the Button "Add", the "Ok" and "Ok".
So the compiler to find the source code of the Components ....

if you are going to recompile a pakage, first close all opened projects, make sure you have only one Delphi instance running and then try to recompile it...

It turns out that the project files got replaced by the component library and just caused a confusion. I basically had to re-add the project's units back into the project and now everything works ok.

Thanks for all the suggestions.

I don't know. It seems as though the author's question was answered by me and two other experts. Even the author's final comment seems to confirm that the component library project was open and not the application project. The other experts may have a mored learned opinion.

What actually happened was the component library objects were somehow merged into the application project replacing several actual project files.