Nios II CPU with debug module not detected

Hi all, I've been getting the message:

"There are no Nios II CPUs with debug modules available which match the values specified. Please check that your PLD is correctly configured, downloading a new SOF file if necessary."

when trying to download my NIOS application to my hardware.

I've figured out the reason for my specific problem so thought I'd let you know in case it's helpful to anyone else:

The problem originates in Quartus not the Nios system.

I had been keeping copies of earlier .ptf files in my QuartusII project design directory, just renamed in case I wanted them back later.

The problem seems to be that when I compile my Quartus project, the compiler finds the other .ptf files and decides to alter the jtag chain details which results in the NIOS debug operation failing later.

I deleted the project .ptf and .sof files and renamed the file extension on all my old .ptf files to something else e.g. name.ptfbak. Generate the SOPC Builder component and compile the Quartus project again so it generates new .ptf and .sof files and and this problem goes away when you use them in the NIOS project.