Samsung S21, S21 Ultra Sim Card Not Detected? Here Is The Fix!

How To Fix Samsung S21, S21 Ultra Sim Card Not Detected

Well, many users report that they are experiencing the problem of “SIM card not detected” error on their Samsung S21 or S21 ultra. These errors are really annoying and disturbing as well.

If your Samsung says no SIM card when there is one, then how can you fix it?

Don’t worry! In this article we covered the proven ways to fix Samsung S21, S21 Ultra SIM card not detected. You can follow the troubleshooting ways and get rid of it.

Nowadays, this issue is common, and many users are facing it and experiencing the worst experience. Well, sometimes it gets worse in such an emergency situation, because once it causes the SIM card error, then you can’t receive calls and not even make calls, receiving notifications.

So, you must have to solve it quickly, before it gets worse.

First, let’s start with the practical scenario!

Practical Scenario: A User Galaxy S21 Displays Error Message “No SIM Card”

No Sim Error S21

I have a S21 5G it’s about 18 months old for the last 6 months-ish, I’ve started having a no sim card error appear, sometimes it will clear if I restart the device other times I have no chance. I’ve had the sim replaced & still nothing, what can I do?

Original Post Taken From – Samsung Community

That is just one scenario there are many users encountering the problem of SIM card not detected.

Also Read: How To Turn On and Set Up Visual Voicemail On Samsung

Now, before going to the troubleshooting ways, let’s know about the causes behind this problem.

Causes Of Galaxy S21/S21 Ultra SIM Card Not Detected Issue

There are some common causes for this problem, some of them are mentioned below.

  • It is not inserted properly, and that’s why it’s causing the problem.
  • Maybe the tray is loose and hence it is not detecting it properly.
  • It might be your SIM is not active.
  • Maybe your card slot has dust/dirt/rust over it, that’s the reason it is not detecting it.
  • Due to your phone cover/case.
  • It could be the update is corrupted. So, it might be the corrupted update was the culprit behind the issue.
  • Maybe your card slot is damaged.
  • Due to Region lock and Network lock.

Now, let’s move to the quick fixes for the issue, you can try the quick fixes before moving to the effective solutions.

Quick Fixes For No SIM Card Error On Samsung Galaxy S21 or S21 Ultra

  • Update your device, may be the outdated OS version is causing the problem. So, update your OS to the latest version, if available.
  • Check if the card is inserted in the correct direction, make sure the SIM is inserted in the correct direction, if you have place it wrong, then it can cause the invalid card error. So, try to place it properly.
  • Check if the SIM is enabled, to check. Go to the Settings and tap on Mobile Network > SIM Card Info And Settings > SIM, after that switch the toggle to the on position. Make sure you also enable Data Roaming.
  • Try removing the case/cover, sometimes the case/cover gets in the way and prevent the card reader from detecting it. So, try to remove it and check fixed or not.
  • If you have updated your phone and it starts showing the problem, then it could be the corrupted update was the culprit. So, to fix it, check for another updates, if available, then update to the latest version.
  • Try inserting the card in another phone, you can try to insert it on another phone to find the culprit. Because if it works fine in the other phone, then maybe your device has an issue. if it not works, then it could be the card was the culprit. So, purchase a new one to fix it.
  • Try to clean the golden point of card, if the golden point has dust over it, then it can cause the problem. So, clean it with soft clothes and do it perfectly.

Your problem can be easily get solved by following these quick fixes. However, if it is not fixed, then you can move to more ways to solve the error mentioned below by following them.

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Now, let’s move to the troubleshooting ways to solve the problem and get rid of it.

15 Ways To Solve SIM Card Not Detected On Samsung S21/S21 Ultra

1. Enable And Disable Airplane Mode/Flight Mode

It might be the service and network settings having some issues. So, try to enable the Flight/Airplane mode, because it can refresh the networks and it can solve the problem. To do so.

  • Simply swipe down from the top of the screen to bring quick settings panel.
  • Now, look for the Airplane mode, to enable it simply tap on the icon.
  • Then, wait for few couple of seconds, then turn it off.

Now, check if the Samsung S21 series still not reading the SIM card, if not, then move to the other effective solution.

2. Enable SIM Or USIM Cards

If you have not enabled the card and you don’t know how to enable it. Then follow the below-mentioned steps.

  • Navigate to the Settings and hit the Connection option.
  • Then, tap on SIM card manager.
  • Now switch on the toggle of SIM or USIM to enable it.

3. Try To Restart Your Device

Well, this is the common and easiest way to fix any errors and problems. The restart workaround can troubleshoot those minor or major bugs and glitches that are causing the invalid sim error. So, it’s better to perform the restart workaround. To do so.

  • Press and hold the Power Key until the Restart menu appears.
  • After that tap on the green Restart button.
  • Now, wait for a couple of seconds until it gets switched on by itself.

Once it gets switched on, then check. If it’s still not reading the SIM card, then it’s better to move to the other solution.

Also Read: Network Locked SIM Card Inserted: Here What To Do!

4. Re-insert The SIM

There might be chances that you have placed the card in the wrong direction or maybe it’s damaged. So, if any of the situations is with you, then it starts showing SIM not detected.

So, try to re-insert it properly. If you haven’t done it respectively, then it may start showing the error again. So, make sure you place it properly and in the correct direction.

5. Ensure Your SIM Is Active

This workaround can help you in finding the culprit. So, first, insert the SIM into another phone, and if the same error you get on another phone then it might be possible that it is not active.

So, try to contact the network service provider and ask them if the SIM is active or not. And make sure your registration is done properly.

6. Turn Off The Radio

There might be chances that the radio signal was the problem. So, it’s better to turn off it. Follow these steps to do so.

  • First, navigate to your phone dialer and dial this number *#*#4636#*#* and make call.
  • Then, you will get the testing menu, then simply choose Phone/Device Information.
  • Now, simply run the ping test, then choose GSM Auto (PRL) from the drop-down list.
  • Now, simply choose Turn Off The Radio, after that restart your phone and check whether the problem is solved or not.

Also Read: Fixed: Can’t Add Card To Samsung Pay On Samsung Phone

7. Change Network Modes

There might be chances that wrong network modes cause the problem. Sometimes, network mode can cause issue.

So, you can try to switch between different network modes and find which is best for you. You can change it to 5G, LTE, 3G, 2G or Auto mode.

These are the steps to follow.

  • Navigate to the Settings, and tap on Connections.
  • Now, go to Mobile Networks, then choose Network mode.
  • Now, simply select different modes, and if you select Auto mode, then it will find the best network mode for your phone, you can give it a try.

8. Update APN Settings Manually

If you don’t know what APN settings do. Well, it is a setting that helps your device to connect wireless services by providing details.

If the APN settings are wrong, then it may cause problems like no SIM card detected, because it won’t get connected to wireless services, if the details were wrong.

So, you need to talk to your network service provider and ask them to check the APN settings. Follow these steps to access its settings.

  • Navigate to Settings on your device and tap on Connection.
  • Now, go to Mobile networks and tap on Access Point Names, then you will able to add APN.

9. Clear Cache Of SIM Card Manager

Well, clearing the SIM card manager cache can fix the problem easily. This feature manages the task of your card services like DUAL SIM, service mode RIL, and the SIM toolkit.

These are the steps to do so.

  • Open Settings on your phone and select Apps.
  • Now, hit the Three (3) dots icon, then select Show System Apps.
  • Now, look for SIM Card Manager, then tap on it.
  • Now, tap on Storage, then hit Clear Cache.

Also Read: Samsung Keyboard Not Working/Not Responding Properly? Here Is The Fix!

10. Clear Cache Of SIM Toolkit

Once you have done the above solution, also try to clear the toolkit cache as it may solve the problem. It carries a little bit same steps just like the above solution. To do so.

  • Open the Settings app and tap on Apps.
  • Now, hit the Three (3) dots icon, then tap on Show System Apps option.
  • Now, look for SIM Toolkit Manager, then tap on it.
  • Then, select Storage, at last tap on Clear Cache.

11. Perform Wipe Cache Partition

If you don’t know what it is, then let me tell you, it’s a cache that is stored on your device’s internal memory/storage. It’s better to clear it. These are the steps to follow.

  • First, connect your device to your PC using a USB cable.
  • Now, long press the side key of your phone to Power Off it, once the settings appear, simply tap on the Power Off option.
  • Now, long press the Side key and Volume Up key until the Samsung logo displays.
  • Now, go to the Wipe cache partition using the Volume Down key, then press the Power key to perform it.

12. Reset Network Settings

This workaround can efficiently solve the problem and bring back the default settings of your phone. But once you reset the network settings, then you have to enter the Wi-Fi password again. Follow these steps.

  • Go to Settings and choose General Management.
  • Now, tap on Reset, then select Reset Network Settings.
  • At last, tap on Reset Settings.

Also Read: [Samsung Help] Wireless Charging Not Working

13. Boot Up Your Device In Safe Mode

Well, this workaround can help you in finding the culprit behind the Galaxy S21 SIM card not working problem. In this mode, third-party apps are not allowed to work.

So, if the third-party apps are causing the problem, then you can find it by booting your device in Safe Mode and uninstall the recently installed app one by one.

And you don’t have to worry about deletion of data or anything, because once you get back to normal mode, your data and apps remain the same.

14. Select The Right Network Operator

If you are using a carrier that is different from your network operator, then it can cause problem of Samsung S21 SIM card not working.

So, try to choose the correct network operator and make sure it’s same as your carrier. Follow the mentioned steps.

  • Navigate to the Settings and tap on Connections.
  • Now, hit Mobile networks, then tap on Network operators.
  • Now, switch off the toggle that present next to Select Automatically, then wait until your device searches for networks.
  • Now, select the desired network.

15. Do Factory Reset

If the problem is still not solved and you are suffering to troubleshoot it, then you can go for the factory reset workaround. But make sure to backup your data before doing it, because it can wipe all the stored data of your phone.

I recommend you to follow the above solution first and if the above solution didn’t help you, then you can go for the factory reset. These are steps to follow.

  • Navigate to the Settings and tap on General Management.
  • Now, select Reset, then at last tap on Factory Reset.

Also Read: My Emoji Keyboard Disappeared On Samsung? Here How To Fix!

SIM Card Not Detected Related Frequently Asked Questions [FAQs]

Question 1. Why Is My Samsung S21 Not Reading My SIM Card?

Answer. It could be the card tray is loose or it has dust over it, that’s why the reader can’t recognize it properly. To fix it, gently push the tray if it’s loose and clean the slot if it has dust over it.

Question 2. How Do I Activate My Samsung Galaxy S21 SIM Card?

Answer. If you have taken the SIM card from Verizon, then follow the steps to activate it.

  • Make sure a 5G SIM is inserted in your phone before you Power on it.
  • Then, keep pressing the Power key until the Samsung logo appears.
  • Now, select a desired language, then hit Start.
  • Now, read the Terms and Conditions, then hit Next.
  • Now, hit Next from the Phone Activation Page, if asked, enter the account PIN, then simply follow the on-screen instructions.
  • Now, choose a network and enter its password from the Set-Up Wi-Fi page. And if you tap on the Skip option by mistake, then you can add Wi-Fi after setup completion.
  • Now, choose a desired option from the Copy apps & data page.
  • Then, create a new Google account or sign in to your existing one. If you by mistake tap on Skip, then you can add account after the completion of setup.
  • Now, from the Google Services page, you will able to see options that are Use location, Allow scanning, Send usage and diagnostic data, simply choose any of them and hit Accept.
  • Now, you can select Not now, if you want to enable screen lock after completion.
  • Now hit Accept option from the Verizon Services page.
  • Then, read and agree the Terms and Conditions from the Verizon Cloud page. If you select Skip option, then you can setup it after the completion of setup.
  • Then, hit Accept option from the Digital Secure page.
  • Now, create a new account or sign in to your Samsung account.
  • Now, simply tap on Done.


Well, sometimes Samsung S21/S21 Ultra starts showing SIM card not detected or No SIM card error, which can disturb you a lot, as you won’t be able to make or receive calls and notifications after this issue.

So, in this guide we provided the proven ways to fix Samsung S21/S21 Ultra SIM card not detected issue. I hope this guide have helped you in troubleshooting the problem, if it does, then do share it as it can help others also.

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