I create a custom superflat world using specific non solid blocks. Non solid blocks can cause problems. My example below uses various buttons. The problem is as soon as there is an update, such as me pressing a button, a bunch of other buttons break and a few seconds later there is a game crash. There is a crash report associated with the crash caused by making superflats out of non solid blocks. Here is some of it:

---- Minecraft Crash Report ----
// Don't be sad. I'll do better next time, I promise!

Time: 11/22/18, 9:26 PM
Description: Exception in server tick loop

java.lang.StackOverflowError: Exception in server tick loop

...

A detailed walkthrough of the error, its code path and all known details is as follows:
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– System Details –
Details:
Minecraft Version: 18w47a
Operating System: Linux (amd64) version 4.15.0-39-generic
Java Version: 10.0.2, Oracle Corporation
Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 421880432 bytes (402 MB) / 1006632960 bytes (960 MB) up to 2147483648 bytes (2048 MB)
JVM Flags: 8 total; -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
Player Count: 1 / 8; [ui['Asadefa'/294, l='World', x=-79.58, y=3.84, z=-74.35]]
Data Packs: vanilla
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

Note: I cannot give the whole crash report because it is too long. Probably the part about "java.lang.StackOverflowError: Exception in server tick loop" is the most important.