NIOS II cannot run from an external memory QSPI?

Hello.

I would check the following items:

1- Make sure Nios II reset vector and exception vector are both pointing to QSPI

2- Make sure you use 25MHZ clock as maximum to the QSPI IP.

3- Try to use PLL for your system clocking. One clock would be for the system.

Please let me know if any of the debug steps would help.