I had something kind of scary happen this past Friday.
I downloaded the Helix version 3.15 software, and ran it. It stopped (froze up) after a few seconds of running. I did notice that it was deleting older version files, which at first, did not alarm me. However, after it failed to continue, I had to close my computer and reboot. Then, when I started Helix Edit, it opened, but was completely blank - no software patches, or setlists, or ANYTHING showed up. (See screen capture, below)
I had already backed up all my patches, so I wasn't too worried about that. So, if experience trouble with the update, you can do the following, and you should be fine.
1 - Download the 3.15 update.
2 - UNinstall ALL the Helix Edit software from your computer ( no need to uninstall Monkey, or Variax Workbench)
3 - install fresh, using the Helix 3.15 update software you downloaded in step 1
4 - install the 3.15 firmware from the Line6 website
5 - perform a system reset (Recommended by Line6)
5 - restore all patches using the saved backup
SO - PLEASE make sure you create a backup before you try to update to 3.15. Also, make sure you do as instructed by Line6, and install the 3.15 firmware after the software update, AND perform a factory reset (on Helix, this is done by holding down buttons 9 and 10 while powering up.) After all that is complete, you can restore your backup. By the way, your back up will preserve any MIDI mappings you've made (I was grateful for that!) including CC's, PC's, as well as input and output settings, IR's, global settings, and any settings such as custom tunings, guitar models, etc.