Known bad firmware versions VESC/UNITY [ SERIOUS ]

This is a manually maintained list of known bad firmware versions for VESC/UNITY It’s a wiki now so you can add to it.

keep the description short and link to some reference thread or other documentation.

Bad versions


Focbox Unity


Firmware 4.02 suffers from motor temperature reading instability that can lead to sudden cut off’s due to faulty readings. As far as I know this is present in all 4.xx versions as well as the wobble bug that was present in the first releases. It was fixed in 4.02 if I’m remembering the patch notes correctly.


I’ll drop a flag there to learn more about it !

@Brenternet, maybe this thread should be linked in the sticky safety thread.

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Brent isn’t a mod fortunately

Maybe signal another mod? Although I don’t see why it should be stickied (yet). We don’t even have a comprehensive list yet, just a few of the many bad firmwares


Great thread! I have to check the FW versions runing on my VESCs!

I am a mod mate. I feel like this deserves it’s own thread though so that it doesn’t get lost


I think it’ll be helpfull for alot of people, also it’s just all about maintaining it and if it were to become stickied people would properly pay more attention to it and maintain it.

Ah, I didn’t see the leader tag so I figured you weren’t one :thinking:

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cool updated the list with that info. could use a link to more details if you have them.

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Is it 5.1 as well? that has the thermal reading instabilities causing people to trigger throttling and faults?
anyone got a link to solid info on that so I can add reference and add it to the list?

this is where I saw that:

wondering if the 4.0-4.2 claim is wrong of if the range includes 5.1

which versions had these bugs?


Why can’t it just be perfect?!?!?

Yes, 5.1 has an issue with the median filter on the motor temp sensors. @BenjaminF ran into this testing on mk3 VESC6 as well.

You can see the spikes on the log i posted there, faults towards the end.

Afaik this is fixed in 5.2 but I’ve not updated yet on my SC100S to test.


got a link to @BenjaminF’s coverage of the issue? or any best reference link about it?


Didn’t (trigger happy) VESC FW 5.0 have the reverse no brakes issue? Worthwhile immortalising that one IMO.

/edit Yes it was. The now infamous “PPM bug”.


I just looked through my post history. I had a discussion in the reply to pictures thread about it with someone else who was getting the same issue, but im not sure if I ever posted the metr log from that ride, so here it is.

The fault is right there at the end (ride was over because street face). As you can see, my motor temp reading looks like my heart monitor when I’m methed up on Adderall. I de-pinned my motor temp sensors from the sensor plug, and its all be dandy since then. Didnt feel like taking the “its fixed in the new FW” frank approach, as I prefer a devil that I know to one that I dont. And this was an easy fix.

Jesus i was going 32mph when I crashed. Fuck.


What’s the issues in 5.2 FW?

so @BenjaminF @DerelictRobot is this a problem with VESC not handling noisy input or is the vesc somehow making the input noisy? was the issue actually understood somewhere and claimed to be fixed in 5.2? any references to that?

because I had the same kind of problem (and crash) on firmware 3.65

but I had considered it a hardware issue?

I note @Deodand saying a fix was in 5.0 for a similar issue.

so… feeling a bit confused what versions to place this issue in. and also if it’s only an issue in combination noisy temperature sensors or something intrinsic to vesc firmware.

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@Venom121212 you are the most recent person I know of to run into issues with fw5.2 on Unity. That was something to do with max duty cycle?

There’s some uncertainty on what can cause a cutout of power from a fault vs triggering a throttle-down response.

In my case I didn’t get a cutout but I had the motor that was hotter spiking into the soft temp limit, causing it to throttle. It caused wobbles at just shy of 30mph but I carved out of them like a champion and then stuck a backflip dismount as I stopped to check my logs.