I get it when seeing the index or any other page within the forums. It just happen after upgrading. I don't know what was the problem, I already reinstalled the product and it's working now, but I had to manually create all my widgets again.
Thanks.
I'm not going to explain every step, I'm just going to show the steps to create a simple plugin that will print a "Hello World" message.
First of all, I'm not a programmer. I have little knoledge of PHP OOP and MVC is tottaly new to me.
If I say something stupid please let me know xD...
Step...