How to fix 'class doesn't exist error'

I keep getting an error when trying to make a class under it’s parent. I initiate the ‘create’ by right clicking on the class directly. When I go to save creating a new class, which should be a child of the parent; it claims that the parent class doesn’t exist. I’ve uninstalled and reinstalled one already because I thought maybe there was a software error, but now I’m not sure. Any tips?

@DarrylW2

Is the issue is only with this class (or) with all new data class you create ?

Below options to try:

  1. Revalidate and Save of parent class

  2. Create a new parent data class and then child class and then test

  3. Cache clear server restart

@PIYUSHSINHA I ended up just scrapping the whole project (not very efficient) because I knew it would only take me a really long day to rebuild. That fixed it! I’ll have to keep your recommendations in mind for the future. They seem more effective than the route I took.