I am currently developing an EV3 robot that sorts colored technic beams. However, the brick will only run part of the program and then generate a strange error code on the brick's screen. The error contains no text, only symbols. The symbol appears as a triangle with an exclamation point on it, and right next to it is an imitation of programming blocks from the EV3 programming software. Does anyone know what this symbol means, and what to do about it?

After further experimentation, I have narrowed down the possibilities. Both MyBlocks that cause the on-brick error contain loops that are configured to loop until a logic variable becomes true. One of these MyBlocks that has that loop contains more blocks after the loop, but the error comes and the program stops before these instructions are executed. Still unable to provide a picture, but does someone know why the EV3 does not like logic loops?

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    Can you add a picture of the screen?
    – pcantin
    Commented Mar 23, 2014 at 0:49
  • I have gotten same issue, although it came up when I pressed 'connections' on the wifi page. I think this error can mean a lot of different things!
    – Sam
    Commented Jan 19, 2021 at 3:07

4 Answers 4


I know that this question is old, but if someone else has this question, I have found that these error messages often appear when you are either trying to access a non existent array (i.e. you copied the block from another project and you did not change the name of the variable) OR when trying to access a value of an array with an index that does not exist (i.e. In an array of size 4 you are trying to access index #4 or index #5)This is how the error looks, BTW

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    An example of this error being triggered is by putting a file access code block in front of the play block without tweaking it in any way. Commented Apr 29, 2020 at 20:46

I had the same problem. I figured out that this is caused by something trying to read something on a numeric array that was not there. well, if that is the problem, use an array function as append and put in the value of what you want, kind of like this:

I need to put the number two in the array "dorp 2", so I do this:enter image description here


I think that it mean that the virtual machine running on the EV3 brick has encountered an unknown instruction.

Perhaps your program has become corrupted or there is an block that is not configured correctly.

I would copy and paste your blocks into a new program and see if it works. If it does not, start a new program from scratch or just copy a little bit of the program at a time and run it in between copies until you find what is causing the error.


I have found that usualy it is a problem with the brick not the program, try restarting the brick and turning off wifi and bluetooth

  • You are somewhat correct, this error appears when you're in the settings tab, but it also shows up when a program is in operation. Just because you have never seen that variant doesn't mean it doesn't exist. Commented Apr 29, 2020 at 20:51

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