The addon is starting before your network connection is ready. Had the same problen. Somewhere is an option like "wait for starting the addon until network is ready".
Or disable the addon, reboot, wait until network is ready and start the addon manually
Wait for network option resolved my problem with vu+/enigma2 addon. Thanks
Just tried you new build 8.0.2e and I have problem with PVR addon vu+/enigma2 client. It working properly on 8.0.1k build but now I'm getting "unknown error when starting addon. Can't start addon".
Very strange but sometimes libreelec not recognize vol+ and vol- on box remote. Every other remote key is working but just no reaction for volume keys. After restart everything goes back to normal. Libreelec 8.0.2a box K8M s905x 2GB / 16GB.