Hi everyone i am really new to this platform and i spend this whole day trying to debug some simple problem: i can't use my app just made because i cannot connect the bluetooth. 
i though this was easy when i looked up in github
receive.aia (4.4 KB)
the function of this app is to send a message and also receive it from a device
Bigggg thanks for helping
Maybe the device is BLE?
I am not sure cause I saw new BLE update message And I have tried to use it instead but it came out the same error i wonder if it is due to the huawei system?or just because I am not really familiar with it:smiling_face_with_tear: thank you soooo much
Your app is in Chinese, so it's harder to follow:
For starters, we need more information about the BlueTooth device you want to connect to.
I suggest getting a BlueTooth terminal app from the Play Store, and using that to try to connect to your device, just to be sure what it is.
As a pre-BLE app, your code lacks tests of is_connected before the transmission attempts.
I see no reason for the Screen1.Initialize disconnect block.
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Got it! I am now aware that I may spend more time to read the tutorial book. Again sincerely appreciate for your help 
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I have an Huawei P30, Android 10. Works well with BLE.
What are the devices you are using? Make & Model
See my site for some clues:
https://www.professorcad.co.uk/appinventortips#TipsBluetooth
https://www.professorcad.co.uk/appinventortips#BluetoothFailure
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i'm using the HUAWEI P40, HarmonyOS 4.2.0 system. Thank you for offering the sites! 
i gonna check it.
The Harmony OS isn't Android but it's close. If you want to use Google Play that's possible https://www.youtube.com/@thatsyisy
The P40 has BLE and also supports A2DP (Advanced Audio Distribution Profile), which App Inventor currently does not support.
You haven't told us what device you are trying to connect to.
I am beginning to suspect your newness to the concept of Bluetooth requires a joke for better understanding.
Alexander Graham Bell (local inventor of the telephone) had just turned away from his apparatus after calling for his assistant Watson. (The very first phone call.)
His apparatus started to ring.
Bell picks up the receiver.
Wrong number.
(End of joke)
So, you do realize Bluetooth is for communication with some other device?
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