Crash when entering the Nether (whether by portal or world load)

[Zarepheth]

After creating the first Nether portal in my world, I stepped into it and waited to appear in the Nether. However, when the Nether started loading, the game crashed.

crash-2017-01-20_23.54.45-client.txt

The crash happened again, when I tried to reload the game from the Main menu.

crash-2017-01-20_23.57.52-client.txt

In both cases, only the client-side crash was displayed in the game's Launcher, but there is also a server-side crash report for a different mod. The server crash occurs 1 or 2 seconds after the client crash.

I've report the server-side crash issue here: Mine Colonies Issue 493

[Zarepheth]

Just had the crash again, as I attempted to load the same world this evening as the one which crashed yesterday evening. This time, however, I only have a client-side crash log; no server-side crash log was generated. Either MineCraft crashed too hard/fast for the other crash or the problem originates with Substratum and the internal server only crashed because of how the client crashed.

crash-2017-01-21_23.08.02-client.txt

[pmardle]

Does it work if you remove the Substratum mod (Backup your world save first before opening without Substratum)

[Zarepheth]

Removing Substratum does allow the game to finish loading.
I played for about 10 minutes before another crash occurred (still in the nether), but I can't tell which mod might be responsible as everything in the stack trace appears to be native Java or vanilla Minecraft.

I also noticed a few holes, I suspect that is where Substratum ore was originally generated but then removed when the mod was removed. I'll have to restore from the backup to fill them.