I can't believe no one has replied to you yet. I'm sure you've figured it out by now, but for those who are searching: the disk on the NAM device was full. You know how on the NAM you have your hard drive for all the data that's collected, but that's not where the OS for it resides. It resides on a flash card. That's probably like a 128MB card, and it's full. Typically in this situation you have to remove the old version of the software from flash before you ftp the new image up there. Now be careful with this because if you are not positive that you have the correct image, you could be temporarily bricking your device. By erasing the old image before loading the new one you're going to have the risk that if it doesn't work that you won't have an image to recover from. So typically you want to FTP the current image down to a computer where you can store the old image, until you're sure the new one works.
You are right Madison, I was recently trying to do un upgrade at this old NAM card, and I had this issue. Sadly, I could not find in my serach a relation of this error with the procedure needed to solve it.
The problem with upgrading this card, is that you need do it in mantenaince mode, here is the procedure (Upgrade examples, Example 1):
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...