Can't connect to server anymore :(

This is a general support ticket template.
Please fill in as much detail as possible.

Before Posting:

Java 8 is required to run our modpack. Not having it will cause you to crash on launch.
Mac OS, Windows, and Linux users can download the Java 8 installer for their system from here.

how did you install the modpack?: installer
have you installed Java 8?: yes
when does the problem happen?: connecting to the server
logs/crash-report: Internal Exception: java.lang.illegalArgumentException: The name acblocks:store_shelf_block has been registered twice, for Block{null} and Block{acblocks:store_shelf_block}.
problem: when I try to log on to the server it says, fatally missing blocks or items. Someone else had the same problem but I have the installer not launcher. I’ve looked through my files and can’t find another entry of the same block. I’m not sure why I would have 2 in the first place. Ive been playing for 2 weeks and been running fine. now its not working.

Going off your ‘problem’ description it sounds like you need to update your modpack (download the installer and run again to update).

If that doesn’t work you’ll need to provide your full start-up log, not just one line.

thanks it worked