This morning I landed a big change to how multirust-rs does self-updates. The transition from the old system to the new has been pretty rough, and I’d recommend on holding off on running
multirust self upgrade for a day or two while I work out the bugs.
If you do try to upgrade and it doesn’t go well, it should be relatively easy to recover by deleting all of the following directories and doing a fresh install. Please do let me know what went wrong though.