I'm going to take a stab in the dark here and assume a couple things......Do I need to flash a newer MM bootloader when I go from TEK 13.7 (based on N920TUVU2DPD1) to 13.8 (still MM, now based on 3DPG1)? Because I get that same error, "Decompressing ramdisk >> Failure, aborting" when it tries to patch the boot image. However, the rest is installed normally and it boots and seems to run fine.
My baseband/bootloader are both DPD1. If I do need a newer one, I'm not sure where to get it anyway. All I can find in Google are requests for people asking someone to upload an ODIN-flashable DPG1 bootloader.
I assume the error occurred whilst flashing in TWRP and you are installing ROM over an existing custom kernel ?
If this is the case, the custom kernel ramdisk may be repacked using anything other that the Chainfire script supported "gzip" compression method, hence it errors during the script.
If you are using SkyHigh kernel, then it will give this warning due to the reason stated above. For my kernel, this isn't an issue, and kernel should be reflash AFTER any ROM flash (after first boot), and ignore the error.
If anything else than my assumptions, then sorry, don't know
SkyHigh kernel == "original" experience, no cheap "Knock off" like most others. Credit given where credit is earned..... not stolen !!