This is a small one — minor firmware updates have been released for the Panasonic LUMIX GH5S (v.1.5) and LUMIX G9 (v.2.1) cameras addressing a possible “picture freeze” while shooting under very specific series of conditions. While I've never run into this myself, apparently if you were…

1. shooting with external flash…
2. and had the camera set to AFC/AFF…
3. and had the LVF set to 120fps…

…then you may have experienced “picture freeze”, which likely means that the image in the viewfinder would freeze up, probably necessitating a reboot. 

The actual release notes say:

Picture freeze may occur at burst recording using an external flash when camera is set to AFC/AFF and LVF frame rate 120fps, has been improved

Download

You can download the update from the Panasonic support page linked below. This isn't a critical update, but even if you haven't seen the bug, yet you do shoot action with flash, then you should install it. If you don't, then I wouldn't worry about it for now.

Download Firmware Updates

How to Install

If you aren't familiar with the update procedure, check out this video here, and scrub ahead to about the four minute mark for instructions on the G Series cameras.

Can you update from an older previous firmware?

I get asked this all the time — “do I have to install the previous updates before I can install this one?” — the answer is NO. Every new update includes all code from all previous updates, and can be installed over any older version of the firmware. So no matter what firmware is on your camera, you can install this update and receive all previous updates along with it.

Panasonic LUMIX GH5S v.1.5 and LUMIX G9 v.2.1 Firmware Updates