The first one is warning considering both the images sport feature set of universalk9.
Second one is a genuine error as if the image needs minimum of 64MB of flash, that is due to .tar images are uncompressed and hence need more space.
when you do manually, rather it is supported or not, it may do it irrespective of consequenses.
But in case you want to do it, there is a workaround to modify the image (c3750e-universalk9-tar.150-2.SE2) and manually change minimum space from 64MB to less.
You can go to software image repository from :
Configuration > Tools > Software Image Management > Software Repository
Click on the image and manually change minimum flash and click update. Try to upgrade again.
-Thanks
-Thanks
Vinod
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