Long story short, I tried to install MultiROM on my Nexus 6P, and it failed. So I tried to restore my backup using TWRP 184.108.40.206, and it keeps failing at exactly 7800MB with the error
E:extractTarFork() process ended with ERROR=255. I have seen posts talking about checking the log when this happens, but I'm not sure exactly how to do that.
What exactly do I need to do to restore my backup?
I guess I should add some detail. I first tried booting to recovery and restoring the backup. The phone rebooted into a boot loop part of the way through the restore process every time I tried that. Then, I tried flashing the phone completely back to the stock image, and then restoring. I got the error 255 above. Then, I tried flashing back to stock completely, wiping Dalvik/cache, and restoring the backup. I still get the same error message. I tried restoring everything except userdata, and the phone reboots part of the way through the restore.
I could easily reroot, reinstall Xposed, and reflash TWRP if for some reason my system backup partition is corrupted. However, I don't want to lose my data partition at all. That was the whole reason I made the backup in the first place.