Error CMP603: The instance <instance name1> of XTL or RC oscillator cannot drive the instance <instance name2> of type CLKINT. Use the macro of type CLKSRC instead of CLKINT here.

CLKINT can take input from the routed nets only. XTL/RC are the hardwired connections and can not be routed.

Action

Use CLKSRC instead of CLKINT.