How to fix HTC U12/U12 Plus that cannot detect SIM card, No SIM card error [Troubleshooting Guide]

When your phone shows a No SIM card error, it is telling you that it does not detect the SIM card for some reasons. This usually happens when the SIM card is loose or not properly inserted in the tray. In worst case scenarios, the error can be attributed to a damaged SIM card or SIM card tray/slot. Aside from hardware and SIM card issues, software errors are also among the causing factors to consider. In fact, many cases of No SIM card errors are attributed to software glitches on the phone.

To help you deal with the same error on your HTC U12/U12 plus smartphone, I have mapped out some applicable workarounds and generic solutions for you to try on. Read on to find out what to do if suddenly your HTC 12/U12 Plus failed to detect the SIM card and keeps showing a No SIM card error.

Before we move on to our troubleshooting, if you are looking for a solution to a different issue, make sure you drop by our troubleshooting page as we’ve already addressed some of the most common problems reported by our readers. Find issues that are similar with yours and use the solutions we suggested. If you still need our help after that, then feel free to contact us by filling up our Android issues questionnaire.

First solution: Reboot/soft reset your HTC U12/U12 Plus.

The phone may be experiencing some random software glitches that may have affected the network functions and that could trigger the phone to prompt a No SIM card error or fail to detect the SIM card. If this is the first time you encounter this problem, then it’s likely just a random glitch, which can be remedied by a device restart or soft reset. Here’s what you should do then:

Press and hold the Power button for a few seconds or until the menu options appear.
Then tap Restart.
Alternatively, you can press and hold the Power button for at least 10 seconds and then release the button when the HTC logo appears.

Wait until the phone is finished restarting then see if that fixes the problem. If the error is recurring, then you’ll need to troubleshoot further.

Second solution: Remove and reseat the SIM card.

It’s possible that your phone is prompting a No SIM card error because the SIM card is actually dislodged from the tray. As a result, it failed to detect the SIM card. To clear this out, you need to remove and reseat the SIM card on your phone. Here’s how:

Power off your phone completely.
Hold the phone face up.
Insert the tip of the eject tool that came with your phone into the tray eject hole. If you don’t have the tool, you can use a small bent paper-clip instead.
Gently push the tip all the way into the hold until the tray ejects.
Then pull the tray out.
Carefully remove the SIM card from the slot then examine it for any signs of damage. If everything looks good, place it back into the card slot. Be sure to place the card with the gold contacts facing down.
Align the cut-off corner of the nano SIM card to the notch on the card holder.
When the nano SIM card and microSD card are secured, insert the tray back into your phone. Make sure the tray is fully inserted and does not protrude from the slot.

Restart your phone and see if the SIM card error is already gone.

Your HTC U12/U12 plus supports a standard nano SIM card. The use of modified card is not recommended because it may be thicker than the standard nano SIM card and won’t fit properly on the tray. There is a chance that it would damage the card slot.

Third solution: Reset network settings on your HTC U12/U12 Plus.

Network connectivity issues may also cause similar errors to show up on your phone. In that case, performing a network settings reset can help. Doing so will refresh network functions of your phone and thereby clears network errors and glitches. Here’s how it’s done:

Swipe up from the Home screen then tap Settings.
Tap System then tap Reset.
Select Network settings reset from the given options.
Then tap Reset settings twice to confirm action.

Allow your phone to instigate the network settings reset process and then restarts when done.

Fourth solution: Update phone software to the latest version available.

Software updates not only offer new features but also contain bug fixes. This is therefore the key to fixing the No SIM card error on your HTC U12/U12 plus if it’s inflicted by some bugs. Typically, you will see an update notification if a new software update is available for your phone. Make sure your phone is connected to the Internet. To view the software update information and download update file, follow these steps:

Then tap the system update notification.
If necessary, tap Update over Wi-Fi only if you don’t want to download the update using data connection.
Then tap Download to continue.
Wait until the download is finished then select the option to Install now.
Tap OK to confirm.

Wait until the update is completely installed. Don’t forget to reboot your phone afterwards to apply the new system changes and likewise prevent any apps from going rogue too.

Fifth solution: Reset your HTC U12/U12 Plus to factory defaults.

If none of the previous methods is able to fix the problem and your HTC U12/U12 plus is still showing a No SIM card error, then you can perform a factory reset or master reset. This process reverts the phone back to its original or initial state. All data stored on the internal memory including your downloaded apps, accounts, personal files and settings will be removed. That said, creating backups would be necessary. Tough bugs and malware are likewise obliterated in the process, thus you will have a clean, same as new device afterwards. Should you wish to proceed, then follow these steps:

Swipe up from the Home screen.
Tap Settings.
Tap System then Reset.
Select Factory data reset option.
Make sure you don’t select the option to Erase SD card if you don’t want to delete media and other data from your SD card. Otherwise, mark the option to clear the SD card contents as well.
Tap Reset Phone.
Then tap Erase Everything to confirm.

Wait until the reset is finished and for your phone to restart by itself. After the restart, you can proceed with the initial setup and set up your phone as new.

Seek more help

Contact your service provider or HTC Support for other options and further assistance if the problem persists. You can request for a new SIM card replacement if you think the SIM card is at fault.

Meanwhile, if the error instigated after you dropped your phone and it persisted after exhausting all applicable solutions, then you’re likely dealing with a hardware issue. In that case, you need to take your device to an authorized service center and have it examined by an HTC technician for hardware damage. Physical or liquid damage may be the main reason why your HTC U12/U12 plus suddenly failed to detect the SIM card.

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