# M-12.2 (Multi-Coin)

The multi-coin firmware M-12.2 update includes the following:

* Fixed the issue of transaction signature rejections in certain scenarios for Polkadot

Tutorial for firmware upgrade:

{% content-ref url="../../getting-started/firmware-upgrading" %}
[firmware-upgrading](https://support.keyst.one/getting-started/firmware-upgrading)
{% endcontent-ref %}