So I got a spare battery for my Spark.  Both times I have used it, when I start up the aircraft, it says latest firmware is installed.  Then, while in flight, I get a warning about firmware compatibility.  Sorry I can't remember the exact wording, but something about an older version of firmware.  Does the battery have firmware separate from the Spark firmware?  If I dismiss it doesn't seem to have any impact on operation, but how do I get rid of this warning?  I can't update the firmware when it's up to date, so....

After launching the app wait for a slider to pop and slide it - it takes about one minute max to update the battery FW which does need to be consistent with the RC and AC. The FW release notes normally indicate if the batteries need doing too and as it's a new battery I guess thats the case.

The battery has firmware, too.  Just put the battery in the Spark, plug the Spark into your computer and go to DJI Assistant 2 and see if an update is necessary.

I had an initial (out of the box) incompatibility, as the spare Spark battery I bought in addition to the Fly More Combo (to get 3 total) was indeed on an older FW version than the 2 that came with the Combo. Didn't discover it until the app wouldn't let me take off with that 3rd battery my first flying day. Rectified it afterwards (learned you must have the battery in the aircraft to update it). It killed my flying for the day, tho, since I live 4 miles from an untowered "heliport" (it's actually sited at an AT&T microwave facility near a local mountain pass). Accordingly I must notify the airport manager in advance each & every time I want to fly (outdoors). My flight plan had a 2 hour window and by the time I tripped across the issue, fixing it then would have put me past my flying window.

In any case, a portion of the aircraft FW includes FW specifically for the battery, so to get it updated I had to install the 3rd battery to the Spark and then (IIRC) "refresh" the AC FW. That took care of it.

But I must say have never had a version incompatibility message while in flight (just pre-takeoff and blocking flight that one time), so that is definitely an oddity. I've got maybe a couple dozen flights on her, and nothing like that has ever popped up. Good luck chasing it down. I'd have to say one dislike (OK, minor annoyance, maybe) about the Spark is the eternal version configuration management necessary across the controller, aircraft, each individual battery as well as the DJI app itself. They've all gotta be in sync or no flying for you and the Spark! And you have full responsibility for carrying out all the necessary CM choreography, each and every time there's an update.

Sir, please enter the general settings-about and then provide a screenshot of firmware info. If it is not the latest one, you can mount the battery on spark and update it with DJI Assistant 2.