I created a project in Project Navigator and generate an IP using a new source wizard (Project -> New Source).
The IP core was generated successfully, but the the following error was logged in Project Navigator Console Window.
ERROR:sim:608 - Unable to close project with ID '829301_Xilinx_coregen'. Project is not part of the design environment.
The error message also shows up when I click the [Cancel] button, instead of [Generate] in IP dialog box.
This problem occurs if the user tries to create an IP core with the name "coregen." When Project Navigator connects to the CORE Generator plugin, the plugin creates a default CORE Generator project called "coregen" (or it loads a project if there's one in the dir). The project and IP core name conflict and the error message is generated.
What will happen is that the second project created (for the ip) won't get added to the design environment (DE) but generation will still continue.
The messages indicating that the 'coregen' project can't get added to the DE that the project can't be closed (because it wasn't added to the DE) can be ignored in this case.