Just updated our FTB Direwolf20 server to 1.7.0 (from 1.4.0)
and got this message

[18:55:46] [Server thread/INFO] [STDOUT]: [de.ellpeck.actuallyadditions.mod.blocks.BlockGreenhouseGlass:func_180650_b:82]: debugg

This was coming in the server console a few times each second and no one could log in to the server.
I restarted the earlier version of the server (same world, config settings etc) with no problems.

I mean, its not a bug, just a bit of a log spam I forgot to remove, but it wont prevent any logins