You need at least 128 meg of memory and 28 meg of flash to run 12.4T code , this is minimum and may not be enough if you are running many features on the box . Do a show version to see how much memory you have .
Glen makes a good point about the memory and flash requirements. The error messages that you posted look much more like memory problems that flash problems. My guess is that the code that you loaded was a significant step up from the code that was on the router before and that you do not have sufficient memory to run this version. It looks like your choices would be to upgrade memory or to go back to somewhat older code.
I checked the requirements for running c870-advipservicesk9-mz.124-6.T6.bin and as Glen indicated it does require at least 128 MB of memory and 28 MB of flash. If you post the output of show version it will show what you have on that router.
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...