What is wrong with Modkit

I have just bought 6 VEX IQ kits. I drove 400 miles and personally checked out each kit for functionality before bringing them home. At first the problems with MODKIT looked manageable. However as I worked with students they became completely impossible:

Modkit is killing VEX IQ for my students.

  1. It fails on the double click in the browser

  2. It throws up unknown error frequently stopping the flow of programming.

  3. No example programs??

This makes the product UNUSABLE!!! When will this be fixed? If it is not soon I will have to return the kits and return to LEGO. 95% right is not good enough.

I am so disappointed.



We are very sorry that you are having these issues. The unknown error is a rare problem that can be caused by specific variable or broadcast event names. We have identified and correctly all known cases that can cause this, and we are currently working on improving the error programming message to alert the user exactly what the issue is. We value your feedback on this item to help us identify and correct any problems that may have occurred.

Regarding double-clicking, this is only a known problem when loading a program from the Browse menu. Modkit is designed as a web application, so like all web sites double-clicking on links will cause web pages to load twice. In rare instances this may cause the program in Modkit to fail to load properly. We are currently working on eliminating this potential issue.

To help provide you with additional help and example programs, please send the .mkc file of the Modkit program in question and a description of the problem that you are having issues with to modkit@vex.com. You can download the .mkc file in Modkit by going to the Project drop down menu then select Download.

For example programs, we are still wrapping up all documentation. If you have any specific questions or would like to see how a specific block is used in a sample program, please contact modkit@vex.com.


  • Art

Chris at Rapid and I are looking at programming difficulties with the Robots. We realise what we need is an example of how you set up the buggy to do a maze using modkit. I am sure you have this. Please could you send me it to gabriel@kyne.co.uk.

I will forward all the files I am having difficulty with to modkit@vex.com.

Hi Gabriel - I’ll look at your various programs and get back to you for each one. Regarding the maze navigation, I have now recieved your psuedo code for what you are trying to achieve so I will recreate this for you in Modkit.

Art - the double click issue is ones of the biggest problems with Modkit in its current form and I would not say that it was rare instances in which the program does not load correctly. In our testing, it will fail to load 100% of the time when double clicking on a project in the browser.

We have a working solution now in the alpha builds of Modkit for the double-click issue.

The double click issue will be solved in the next Modkit update, that we are aiming to release within the next 7-10 days (it will also have a bunch more features/fixes). We want this update to be released before VEX Worlds with enough time for teams to use the new features, but due to the nature of software development we cannot confirm a specific date for this release.

Is there any update on this release Art?


Both fortunately and unfortunately, this next release of Modkit has a lot of behind the scenes upgrades and code refactoring. On the good side this means it will make it much easier to add in some really cool features, but on the other side this means we need to do a lot of testing. We want to make sure everything is working great and it does not cause any side effects. Our other really big concern right now is the VEX World Championship - due to the online nature of Modkit we do not want to unveil any major changes or software updates that might disrupt teams in the week before this event.

Excellent, sounds very positive Art. Makes sense re. worlds, looking forward to seeing the updates!

The release was finally fully tested and then released on April 17th. The double click issue should be fixed in this release and as Art mentioned it includes many other fixes and new features including coordinating multiple motors in a single “Drivetrain” block. Enjoy!

Also we have improved the “unknown error” issue in this release. Now any error compiling the code will return a clearer message which you can post on the forum for a workaround and so that we can fix any underlying bug. As we get more feedback and can plug any remaining holes, the platform becomes more and more stable. Thanks again for your feedback!

Awesome, will have a play around with it today!

My new team has been trying to get ModKit to work. We cannot find any sample programs or manuals to help us get started. It has crashed and we have a difficult time getting Modkit to sync with the browser program. I think we will move to RobotC. RobotC seems to have great documentation, and sample programs for beginners. I assume most teams are using RobotC for VEX IQ? Thank You Alan

We made a video demonstrating how we used Modkit to program a VEX IQ robot to go through a maze. Here is the link: https://www.youtube.com/watch?v=A8urJvD2RrE

I am receiving an error message for several of my students’ robots using different computers in my class. They are all receiving the message below. Any ideas? TIA!modkit%20error

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This post is literally 5 years old, so making a new post would be a better option than reviving this.

Please post your students’ code as this will provide the forum community at least a chance of solving your issue.

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