DJI firmware versions do not match: how to fix inconsistent firmware

"Firmware versions do not match" (or "inconsistent firmware") means one part of your DJI system runs a different firmware version from the drone. It's usually a battery: DJI's manuals say the battery firmware is included in the aircraft firmware, so a spare that wasn't in the drone during the last update is now out of step. The fix is to put that battery in the drone, power on, connect to DJI Fly with internet access and accept the update it offers.

Fix a firmware mismatch — DJI's manuals say battery firmware is part of the aircraft firmware, so every battery has to be inserted and updated after a drone update.

Why it happens

Your drone, remote controller and each Intelligent Flight Battery all carry firmware. When you update the drone, only the battery inside it gets the matching battery firmware. Common triggers:

A spare battery that sat in the bag during the last update.
A new battery bought later, which shipped with older firmware.
A battery borrowed from another drone on a different firmware version.
A second controller that hasn't been updated or linked yet.
An update that was interrupted, leaving one module behind.

DJI Fly may limit what the drone can do until everything matches, so fix it before you head out to fly.

How to fix it

Charge first. For updates, DJI's Mini 4 Pro manual asks for at least 40% on the flight battery and 20% on the remote controller. More is better.
Connect to the internet. DJI Fly needs a connection to download firmware. Use solid Wi-Fi on the phone or on a screen controller like the DJI RC 2.
Link the controller. DJI says you can't update if the controller isn't linked to the aircraft.
Insert the mismatched battery and power on the drone. DJI Fly should prompt you to update. Accept it and don't touch anything until the drone restarts.
Repeat for every battery. Power off, swap in the next battery, power on, and accept the prompt again. Number your batteries so you don't miss one.
Restart everything once all batteries are done, and check that the message is gone.

DJI's Mini 4 Pro manual says a firmware update takes about 10 minutes, and it's normal for the gimbal to go limp, the status lights to blink and the drone to reboot during it. Don't unplug or power anything off.

If DJI Fly won't fix it

Close and reopen DJI Fly, then power-cycle the drone and controller. A prompt sometimes appears only after a fresh connection.
Update the controller separately. If the controller is the part that doesn't match, update it while it's linked to the drone.
Use DJI Assistant 2 (Consumer Drones Series). Connect the powered-on drone to a computer by USB-C, sign in, select the device and choose Firmware Update. DJI's manual says to update the aircraft and remote controller separately. To update a stubborn battery this way, put it in the drone first.
Retry with a different phone if downloads keep failing.

If the same battery never takes the update, or shows warning lights afterward, see DJI battery error.

Avoid it next time

Before updating, gather every battery and the controller you fly with.
After the drone updates, cycle each battery through the drone on the same day.
When you buy a spare battery, insert it and check for an update before your first flight with it.

For more on stuck or failed updates, read DJI firmware update error and how to update DJI firmware. If you need another battery, the Mini 4 Pro Intelligent Flight Battery is one example. Insert it and update it before its first flight.