trying to update my RGH to 17489 and i get this error.
You're getting the error because it's detecting that you're using your Retail nand dump.
Rather than a flashdmp.
If you used Flash360 or Simple 360 Nand Flasher, to read back your current hacked image, the error wouldn't be there.
But because that is the retail nand dump image, it has a clean (non hacked) SMC.