Help Needed Troubleshooting the Live Remote Practice Matches

So I have been searching the forums and haven’t found much yet related to the REC foundation’s Live Remote Practice Match system so here goes:

We finally set up a space in our school robotics shop to do remote events and we were very excited to try out the remote practice match system but we have run into a snag.

The Problem:
The webcam connects correctly but it seems like the problem is with the controller. It loads a screen to allow me to connect to the controller but then gets an error when I press connect. Digging a little bit deeper it looks like there’s an issue with the SerialPort. I’ve included a screenshot of the error as well as the developer console below:

An Error has Occurred - In Context with lobby and url Developer Console JS Error

Things I’ve Tried:

  1. Verified that the teams I am signing in with have been properly registered through robotevents
  2. Verified multiple times that “Experimental Web Platform Features” is enabled and Chrome was restarted.
  3. Verified that the firmware on the controller, brain, and receiver are all up-to-date. I literally watched my students perform the update.
  4. I tested the system on Chrome running on Linux and Windows 10 and in both cases encountered the same error at the same point.

Any ideas how to get this working? Are we the only ones with these problems? Why aren’t there more conversations and videos about people using this system for practice matches? If anyone could assist us that would be awesome!


did you enable experimental features for chrome ? web serial only works if that is enabled.


Yep. Did that (things I’ve tried #2). I don’t think it’d be able to even SEE the controller at all if experimental web features weren’t enabled. I can see that there’s a V5 controller to connect to but then it errors out when I press connect.

yes, sorry, that’s my fault for not reading your post fully.
let us do some digging at our end and get back to you.


any chance you are running chrome 86 ? looks like there may be an API change that google implemented.

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The version I’m using is 86.

In the settings it says:
Google Chrome is up to date
Version 86.0.4240.75 (Official Build) (64-bit)

We tested on our linux system using Chrome 84 instead of 86 and it works! Now just trying to have our web camera fit the frame properly… 7 feet by 7 feet still isn’t quite far enough distance.

RECF pushed a fix for the chrome 86 issue. It should be working now on your original system.


If 7’/7’ is not enough to frame the field, try a 120 FOV webcam. This is the one on Amazon that we found works well while not destroying our budget (it is not 60fps but 30fps but the other specs are legit)

Not sure if you are on the dev team but I’m hijacking this thread (sorry mods) as I don’t want to offend the REC by starting a winy/negative thread, I know they did an amazing job making all this possible in such short time (at my day job if things got done this fast and this effective, then omg…) We just set up a cam and a laptop and a projector, cleaned our room, reorganized everything and were super excited to meet this Saturday and try the live remote practice system. Here are some observations:

  • Matches are not labeled as IQ/VRC. We are VRC and were very excited to see 3 open 1v1 matches but could not join because those were IQ matches. Labels would help.
  • It is not possible to initiate a chat with teams sitting in the lobby. There were 2 teams that looked like VRC (as per but my team did not know how to get in touch with them. We thought that out of the tens of thousands of teams in the world we would definitely find a random match to play on a Saturday evening lol.
  • This one is technical: You can only initiate a match if controller is on and connected, if robot is on and running the program. Once any of these things are not satisfied, the software throws an error. The result of this is that we literally sat and waited for someone to join our match or for someone to create one and our robot battery slowly dropped to 30% (curious what is eating the battery that fast, we have no pre-auton running). Battery gauge on the web interface great touch by the way. We are a single team with one robot and plenty of restrictions about meeting so the result was a wasted day. Again, this is not to criticize anything/anyone but we are simply trying to figure out how to utilize the system to keep my team engaged. Should we buy a second brain and hook it up, initiate a match then let it sit and wait for someone to join (I know the answer is find friends with fields and similar schedules but…) so the team can still work on/with their robot? Will switching to another controller/brain break the session? Is there any other setting/trick we don’t know? Thanks.

I’m not, this is an RECF run project.

Have a look in the V5 brain dashboard and see how much current is being used when your program is just sitting idle. You should probably see < 1A. You could also connect the battery charger while you are waiting, that should help.


“Why didn’t we think of that?” Thank you.


I am new to Vex, but have a strong IT background.

I have followed all the posts here, and can’t seem to get the controller connected it just hangs on the “no compatible devices found” screen. I have downgraded Chrome to 84, have the field controller plugged into the laptop, to the driver station, and the robot controller plugged in. I have tested using the tournament software that the computer sees the field controller and can stop the robot from driving. So, not sure what I am doing wrong. They will be doing an online tournament on 12 Dec and we need to get them up and running.

Thanks for any help!

The Live Remote system does not use official field control hardware. Instead, the controller is simply connected to the computer using a USB cable, and the computer issues the field control commands using this link. No connection to the “Competition” port on the controller is necessary.


Thank you very much, it is now working. There are too many “controllers” and the instructions did not say, “robot” controller.


Thanks for the suggestion! We’re using a super cheap one so that might be why we are having wide angle problems. But it’s been enough to allow us to compete and only $20.00.

I’m sorry to hear that things have been frustrating for you. Has anything improved since November? I found all the connection issues to be incredibly annoying too. Not sure why we can’t have the camera be the main connection then have the controller and program and such things be set up once you join a match. Or at least not have it throw a massive fit if one of those things becomes disconnected.

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If anybody is still experiencing issues, please reach out to! Our entire team here at the REC Foundation will be thrilled to assist! We’ve learned a lot, and made many changes during these past few months, so we hope you aren’t experiencing these same issues. I hope that you will join us for a Live Remote Tournament soon (they happen in the evenings during the week and on most Saturdays). See you there!


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