In this post I want to show you something that happened to me yesterday. I have SQL Developer installed in a virtual machine with Windows and when I opened it I got the following error:

After searching and searching I found that you can delete a folder within the SQL Developer installation and then allow you to reopen it without a problem.
Tienes que ir a tu instalación de SQL Developer, por ejemplo en mi caso es:
C:\Users\<nombre de usuario>\AppData\Roaming\SQL Developer\system22.2.1.234.1810\system_cache

Delete the folder system_cache.
Now you will be able to open SQL Developer without any problem 🙂

See you next time!
