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.
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.