IP was not found in qsys

[Altera_Forum]

I'm using quartus prime lite edition 17.1 to open qsys. I open a correct design and there are some errors. The reason is " IP altera_pll was found in the ip catalog" 

 I don't know how to resolve it.

[Altera_Forum]

Just delete and re-add the PLL component to your system design.