Some Android devices show a strange error on dialing numbers that start with * (asterisk) and end with # (hash). Such numbers are generally the service numbers or device utility codes, eg. numbers to quickly flash your balance, IMEI code etc.

The error, when occurs, reflects the following string: “Connection Problem or Invalid MMI Code“. It is annoying, as it doesn’t let you use the important service utilities offered by your operator, not even a talktime balance check.

The below screenshot is a visual display of the MMI Code error occurred on Android 4.9 ICS.

Connection Problem or Invalid MMI Code Error on Android

This is how the error looks like

How to fix this error

I was really fed up of getting MMI code error prompts before I found a quick solution to this problem. While my research, I also found couple of more ways to get rid of that. I’m sharing all the fixes below in this post:

Add a comma (,) at the end

This fix won’t include installing an additional package or app on your Android. When dialing a number, say *123#; just add an extra character , (comma) at the end of the number (i.e. *123#,). Doing so fixed the error at my end, but a few of my buddies are still complaining about this quick fix.

Add a plus (+) after asterisk (*)

This one is sent and recommended by Argo Patel of Kolkata. For instance, if the number is *121#, dial it as: *+121#.

Android Safe Mode

In Safe mode, you may figure out if some app is messing up with the Android operations to prompt this error. To start your Android phone in safe mode:

  1. Turn-off your Android device
  2. Press and hold the power button, and tap the menu button few times while doing so.

The label “Safe Mode” on the bottom-left signifies that your Android device is started in Safe mode. As Safe mode runs only the system apps, you should try dialing a number and see if it still throws error. If it does, there is an app that is causing the MMI Code error. You may now uninstall the recently installed apps to fix it up.

Hope anyone of these worked for you too, kindly share with us the fix that solved your problem. G’day!