Probably you have /etc/opkg.conf pointing to an version's download repo, and package downloads fail.
rc2 has enabled package list signature checks, and this makes old versions' download repos to fail. If you have preserved settings in sysupgrade, your opkg.conf points to the wrong download repo.
The correct location definitions are like this (note the "chaos_calmer/15.05-rc2"):
src/gz chaos_calmer_base http://downloads.openwrt.org/chaos_calmer/15.05-rc2/ar71xx/generic/packages/base
src/gz chaos_calmer_luci http://downloads.openwrt.org/chaos_calmer/15.05-rc2/ar71xx/generic/packages/luci
You should be able to install luci gui with rc2 by using one of these methods:
1)
* install rc2 without preserving settings in sysupgrade.
(You need to re-create all your settings. Restoring a backup will overwrite opkg.conf, so it can't be used)
* login into system console
* install luci normally: "opkg update", "opkg install luci"
2)
* install rc2 while preserving old settings in sysupgrade
* login into system console
* update /etc/okpg.conf to point into the rc2 binaries. Easiest way might be to copy the correct file from /rom:
"cp /rom/etc/opkg.conf /etc/opkg.conf"
(alternatively: edit opkg.conf manually and correct all download repo definitions)
* install luci normally: "opkg update", "opkg install luci"
(Last edited by hnyman on 18 Jun 2015, 08:59)