but IAR debugging is failed
Can you let me know the debugger that you are using?
I guess, IAR can't connect to MCU when enable EXCO
Were you able to debug the device when ECO is disabled? If that is the case, did you also disable PLL?
Also, can you please share the screenshot of the debugger settings? What is the reset mode that you have selected? Please refer to this KBA and let me know if it helps - Debug pointer does not reach main() when using Keil uVision and ULink2/Ulink Pro Debuggers - KBA229982
Thanks and Regards,
Rakshith M B