●Change8

Migrating to BitsAndBytes 0.49.2

Version 0.49.2 introduces 1 breaking change. This guide details how to update your code.

Released: 2/16/2026

1
Breaking Changes
1
Migration Steps
4
Affected Symbols

⚠️ Check Your Code

If you use any of these symbols, you need to read this guide:

quantize/dequantize ops8bitoptimfsdpAdEMAMix scheduler

Breaking Changes

●Issue #1

The default blocksize for 4bit quantization on ROCm devices has changed from 128 to 64. If you relied on the previous default of 128 for 4bit quantization on ROCm, you may need to explicitly set blocksize=128 in your configuration to maintain previous behavior.

Migration Steps

  1. 1
    If using 4bit quantization on ROCm and expecting a blocksize of 128, explicitly set blocksize=128 in your configuration, as the default has changed to 64.

Release Summary

This release introduces new 4-bit quantization blocksize support for CUDA (32) and ROCm (64), updates the ROCm build to version 7.2, and fixes several bugs related to 8bitoptim/FSDP and tensor handling.

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