PSA: New Firmware Update Causing Issues (Received Length Doesn't Match)

Upgraded your firmware recently and receiving an error somewhat along the lines of “Received Length Doesn’t Match”? This is an issue if your PROS CLI is not up to date as this was fixed in an update about a year ago.

If using Atom, use our installer to update PROS:

If using VSCode, make sure that auto checking for updates is enabled and you should receive a prompt to update the CLI.

If your PROS is up to date, make sure your controller and brain are also up to date (these need to be seperately updated).



How do I know if PROS is up to date or not?

The latest version is 3.2.3, and you can check what version you’re on by typing “prosv5 --version” into a terminal.

Being an open source project, you can check what was changed directly here:

Why is this happening?

Long story short, newer versions of VEXos are not compatible with older versions of PROS. The cutoff was at VEXos 1.0.13 and PROS CLI version < 3.2.0. Many users are now finding out that their older version of PROS (< 3.2.0) and newer version of vexOS after being mandated to update to 1.1.1 for worlds and other tournaments aren’t compatible.

How do I update my controller?

Assuming your brain is now up to date via the VEXCode utility, you can plug your controller into your brain and it should start updating.

VEX KB Tutorial:

VEX KB Tutorial for Updating your Brain:

Why is the PROS account not posting this?

uhhh I may have forgotten the password and don’t feel like digging into my password archive and grabbing it.

it’s lost in the sauce so to speak

Where’s the next PROS update?

soon, we’re all busy with exams and school work. but very soon, everything’s ready but we just need to go through the release process(es).