java.lang.IllegalStateException: BufferBuilder not started

What the log looks like

java\.lang\.IllegalStateException: BufferBuilder not started

How to fix it

1. If you are using shaders, turn off your active shader pack in Video Settings before loading the world, as custom block renderers (like Create's Blaze Burner) frequently trigger this error with certain shader packs.
2. Open the crash report and look at the lines immediately below `BufferBuilder` and `VertexConsumer` in the stack trace to identify which mod owns the broken renderer (for example, `polydungeons.client.ber...`).
3. Update both the identified content mod and all of your rendering mods (Sodium, Embeddium, Iris, Oculus, Roughly Enough Items) to their latest compatible versions.
4. If you are using Create alongside Sodium or Embeddium with shaders, install a dedicated compatibility addon such as **Colorwheel** or **Iris/Oculus Flywheel Compat**, or run `/flywheel backend off` to bypass custom instanced rendering.
5. If the crash still happens whenever a specific modded block is on screen, temporarily disable your rendering optimization mod to break the block, or remove the incompatible content mod.

Check your own log