Hi Guillermo As I explained to Stephane, unfortunately I am not able t remember exactly what I did as I didnât notice the problem until sometime later. I assume I removed it through the UI. I have since been working with programmatically creating subclasses having exported the relevant packages to a fresh image. It all seems to work as expected. Regards R From: Guillermo Polito <guillermopolito@gmail.com> Reply to: Any question about pharo is welcome <pharo-users@lists.pharo.org> Date: Monday, 10 January 2022 at 08:47 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Cc: Robert Briggs <rbriggs2009@me.com> Subject: [Pharo-users] Re: Ghost subclass Hi Robert, Can you tell us how did you remove the subclasses? Was it through the UI? Which option? Or was it programatically? Can you reproduce it? G El 8 ene 2022, a las 18:25, Robert Briggs via Pharo-users <pharo-users@lists.pharo.org> escribió: Hi I currently have a problem that I am unable to resolve. I am working on a personal project. I created a Class âERAElementâ and four subclasses: âComponentâ, âCriticalIssueâ, âDecisionâ and âRequirementâ. A while ago I removed he subclass Component, and naturally Pharo will not let me create an instance of this subclasses. However it is still listed in the ERAElement subclass collection. As shown below. <image001.png> I can test for existence of each subclass as shown below: <image002.png> However the same code will not accept Component as a possible value. <image007.png> I can even create a new Subclass Component and get two (different) subclasses with the same name. Any thoughts as to what is going on and if so how to resolve the problem? Many thanks in advance for any and all feedback. Kind regards Robert Briggs