A message stating “Connection problem or invalid MMI code” may appear from time to time, which can be aggravating. When the invalid MMI code message appears, it usually means that you can’t make calls or send text messages until the problem is resolved. This can happen for a variety of reasons. There are, however, a few potential solutions to the Android “Connection problem or invalid MMI code” error. Consider the options listed below. If one process fails to solve the problem, try the next.

What exactly is an MMI code?

Any SIM-compatible device has so many codes and numbers that it can be challenging to figure out what each one is for. An MMI code (Man-Machine interface code) starts with an asterisk (*) or pound (#) sign and allows users to enable or disable various star code functions (*#06#, for example, to reveal IMEI).

The error message “Connection problem or invalid MMI code” that appears on your phone could have been caused by several different things. The primary cause is an issue with the carrier service provider, as well as problems with the authentication of the SIM card on the smartphone. The error is most common on phones with dual-SIM capabilities, but it can also occur on other devices.

Methods for resolving the MMI code error

On Android devices, the “Connection problem or invalid MMI code” error can be resolved in a number of different ways. We’ll start with the most straightforward approach and work our way up to the more complex strategies.

On Android devices, the “Connection problem or invalid MMI code” error can be resolved in a number of different ways. We’ll start with the most straightforward approach and work our way up to the more complex strategies.

1. Reboot your Android device

 Restarting the mobile device would be the first step in attempting to resolve an invalid MMI code on the device.

1.  Press and hold the Power and Home buttons simultaneously until the phone turns off and vibrates; wait for it to restart.
2. Alternately, to restart the device, press and hold the Power button until the Shutdown options menu appears, and then select Restart from the menu.

 2. Boot into safe mode on your device.

There is a possibility that third-party applications are the source of the MMI error, as it is interfering with your connection. The good news is that this possibility can be quickly fixed. Here’s what you should do:

1. To enter Safe Mode, you will need to restart your phone. If you hold the power button (button combination) on your phone, it will allow you to do this. Then, continue holding the Power button for several seconds.
2. From the menu that appears, select Safe Mode.
3. Now, restart your phone in Safe Mode to see if the MMI error appears.

If your phone does not generate error codes, third-party software interferes with your network. You’ll need to start getting rid of apps from third-party developers. Begin with the applications you installed around the time the error first appeared.

Go to Settings>Apps, scroll down, and uninstall any apps you suspect are the blame. Then, remove your phone from Safe Mode and check to see if the error has appeared. Continue doing so until the MMI code stops showing up.

3. Make use of Airplane mode

Airplane Mode has been successful for some users in resolving MMI code error issues they have been experiencing.

1.  Go to Settings and enable Airplane Mode.
2. Wait 10-30 seconds before turning off Airplane Mode.

If you perform this action, you will be able to reset your connection and fix the MMI Code error. This is because a weak signal strength can cause an MMI Code error.

4. Reset your network configuration

As the MMI error is related to your cellular connection, resetting your Network Settings is the next logical step. Chances are that there is something wrong with the system, or the settings for your network might not have been updated correctly. A network reset will clear any error codes and allow you to start over. Here’s what you should do:

1.  Go to the Settings section on your Android device. Then select General Management. To skip step 2, click the search icon and type ‘Reset.’
2. Scroll down and select Reset.
3. Reset Network Settings should be selected.
4. To confirm, tap Reset settings. The phone will reboot.

After you have restarted your phone, you should not see the error again.

5. Change the prefix code

Adding a comma to the end of the Prefix code is another way to resolve the Connection Problem or Invalid MMI Code on an Android smartphone. When a comma is added, the operation is forced to run, and any errors are ignored.

Presented here are two different approaches to modifying the prefix code.

1.  If the Prefix code is (*2904*7#), add a comma at the end, as shown here (*2904*7#,).
2. You can use the + symbol after * as in (*+2904*7#).

6. Turning on the radio and IMS over SMS

To turn on the radio and IMS with SMS, you must follow the instructions below. This solution should resolve your MMI Code error message. 

1.  Navigate to the Dial pad.
2. Enter (*#*#4636#*#*) NOTE: You don’t need to press the send button; it will automatically appear in the Service mode.
3. Go into Service mode.
4. Choose either Device or Phone information.
5. Choose “Run Ping test.”

 Your device will restart after you click the Turn Radio Off button.

7. Try getting a new SIM card

If you have tried all these solutions provided above, but the error still persists, you might have to contact your mobile phone provider to receive additional information. They may suggest a new SIM card or resend OTA (over-the-air activation).

Conclusion

Finally, there are a few methods/options you can use to fix the MMI error on your phone, some of which are a little more complex than others. Although most MMI errors appear on dual-SIM phones, they can also occur on single-SIM phones due to weak signals or tower network issues. Contact your service provider for help if the above steps don’t resolve the issue.