(I hadn’t touched luci at all)
I’m curious how this happened.
I can do this and cause the error to appear:
$ echo "foo" >> /etc/config/luci
$ uci show luci
uci: Parse error (invalid command) at line 41, byte 0
Does uci show luci give you hint about where the parser has barfed?
It fixed itself after restarting luci/uhttpd/nginx/rpcd - I think I caused it by having the connections window open while a terabyte of traffic went through.