• Verification Error

  • amp138

    November 21, 2019 at 4:21 am

    Hi all,

    I’m getting an error on both my controllino mini boards. I have searched and searched for answers and all I can find it my bootloader size might be too small or I need to burn my bootloader.

    However, my issue seems to be unique to others. I have errors (such as quoted below) but sometimes the error is removed by uploading a second time. Other times it won’t disappear upon re-uploading but if I leave it for an hour and try again, the sketch will upload with no problem. I have fun complicated programs and very simple programs and they sometimes upload.

    The code that produced the below error is:

    “void setup() {

    // put your setup code here, to run once:


    pinMode(4, OUTPUT);


    void loop() {

    // put your main code here, to run repeatedly:

    Serial.print(“Hello Worldn”);

    digitalWrite(4, HIGH);


    digitalWrite(4, LOW);



    The verification error it is producing is:

    “Arduino: 1.8.10 (Mac OS X), Board: “CONTROLLINO MINI”

    Sketch uses 1948 bytes (6%) of program storage space. Maximum is 32256 bytes.

    Global variables use 198 bytes (9%) of dynamic memory, leaving 1850 bytes for local variables. Maximum is 2048 bytes.

    avrdude: verification error, first mismatch at byte 0x0042

    0x8a != 0x8f

    avrdude: verification error; content mismatch

    avrdude: verification error; content mismatch”

    If anyone has some guidance, your help is greatly appreciated.

    Kind regards,


  • Lukas

    January 22, 2020 at 1:45 pm

    Hi Aidan,

    please see our FAQ#10.

    We are not able to reproduce it here, but still trying to find the root cause.

    It seems to be somehow related to the






  • Lukas

    February 28, 2020 at 3:08 pm

    I have some news regarding this topic – we have found some potential root cause of these troubles in the original Arduino bootloader.

    Please see this tutorial THIS TUTORIAL how to update to the new MINI bootloader.

    • MariusPWFT

      November 10, 2023 at 4:55 pm

      Hello Lukas,

      we have the same problem with the MINI on our industrial Products. Can you share the Link to the solution?

      Thank you in Advance

  • PeterBately

    January 29, 2024 at 12:26 pm

    It is crucial to have a thorough verification process in place to minimize the occurrence of these errors and maintain the integrity of our data.

    Available here https://vittydrivingschoolllc.com/behind-the-wheel-lesson/ Behind The Wheel Lesson in Santa Clara C

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