Plugin Error : This item does not exist

I also put the plugins in the xojo plugins folder only. For organising the plugins i put your plugins under mbs folder and it works ok on another system. This is a new Windows system and dont have any antivirus installed.

Are you compiling as 32-bit or as 64-bit? Have you tried the other one?

Do me a favor and put all of the plugins you are using directly in the plugins folder with no sub folders. Please take a screenshot of that and post it here, and then try relaunching the IDE. Make sure the IDE is actually quitting though… after you’ve closed it, make sure it’s not still running in the system tray.

I have put all the plugins together in the Xojo Plugins folder
Screenshot 2021-08-13 141122
I have restarted my PC and still the error is showing.

Your missing CoreClasses which the TreeView has dependency on.

That is the problem right there.

OMG. I cant believe and that was the exact problem. Once i coped the CoreClasses and its working straight away. Why would this shows errors in MBS Plugins that the item does not exist. And for particular project i only used MBS plugins. At least Xojo should have alerted that some dependency is missing or similar.
Anyways thanks Bjorn and others who tried to help me. Let this thread may help some one with similar issue.

It’s a long standing issue that Xojo doesn’t show proper compile errors in that case.