Error 503: not a valid mac adress (arduino +HC05 + App inventor)

Hello everyone,

I try to make this application:--> sending a value from a potentiometer via bluetooth-module HC-05 to android phone by following this tutorial:

In a first atempt, I made the app myself. When downloaded to my android phone, I received the error 503: the specifeid address is not a valid bluetooth MAC address.

Because I couldn't solve this error with the help of internet, I downloaded the completer project directly from the electronoobs website and Installed it with the MIT app to my phone. And again I receive the error 503 again!
The error occurs when I click on the button to connect bluetooth in the app itself.

MIT App blocks:

Arduino code:

I don't find many solutions on the internet. It seems I am doing something very wrong but without any idea what it could be.
Can you help me with this problem?

Do you understand the English words "after picking" and "before picking"? If you know what this means, take a look at your blocks and think about their use.

1 Like

You dont have to be so mean. He missed a small mistake thats it