How to Fix Invalid SIM Card or No SIM Error on Android and iOS

An "invalid SIM card" or "No SIM" error means your phone cannot communicate with its cellular network, usually because the SIM card is loose, dirty, or damaged, or because a temporary software glitch has disrupted the connection. Before you replace the card or visit a repair shop, the steps below, starting with a simple restart and re-seating the SIM, resolve the vast majority of cases on both Android and iOS.

Why your phone says invalid SIM card or no SIM

The error appears when your device cannot read the SIM card properly. Common causes include a loose physical SIM that has shifted in its tray, a temporary software glitch that confuses the phone's radio, a carrier settings issue that prevents authentication, or an account or carrier lock problem that ties the phone to a specific provider. Knowing the cause helps you pick the right fix without unnecessary steps.

First fix for any phone: restart and re-seat the SIM

This universal first step is documented by both Apple and Samsung. Restart the device to clear temporary data that may be interfering with SIM detection. If the error persists, power off the phone, then physically remove the SIM card. Inspect the card for visible damage or dirt, and clean it gently with a soft, dry cloth if needed. Reinsert the SIM card, making sure it sits correctly in the tray and that the tray closes completely without being loose. Apple says a SIM tray from a different iPhone, iPad, or another phone manufacturer might not fit properly. Turn the phone on and check for the error.

Fix an invalid SIM on iPhone: carrier check and more

Apple’s documented path, which applies to iPhone or iPad and separates guidance for eSIM and physical SIM devices, begins with verifying your carrier plan. Open Settings > General > About. Next to Carrier Lock, if you see No SIM restrictions, the iPhone is unlocked; otherwise, it can be used only by the carrier it is locked to. On iPhone, to check carrier lock, open Settings > General > About; if unlocked, 'No SIM restrictions' appears next to Carrier Lock. If the device uses eSIM and the error continues, contact your carrier directly. For a physical SIM, restart the iPhone, then check for a carrier settings update in Settings > General > About, if an update is available, you will see OK or Update. If the problem remains, remove the SIM tray, re-seat the SIM, and ensure the tray is fully closed. On iPhone, to manually select a network, go to Settings > Cellular > Cellular Network, turn off Automatic, and pick the right network from the list. Trying another SIM card can help you determine whether you need a replacement; for details on costs and processes, see the SIM Card Costs, Functions and Replacement Guide.

Fix a no SIM error on Samsung Galaxy: network reset

Samsung’s documented steps, which apply to Samsung Galaxy devices, go beyond a restart. First, remove the SIM card and tray, then clean both with a soft, dry cloth. Reinsert the card, making sure it is seated correctly. Next, turn on Airplane mode from the quick settings panel, wait a few minutes, then turn it off and test again. If the error persists, reset your mobile network settings by going to Settings > General management > Reset > Reset mobile network settings > Reset settings > Reset. This restores Wi‑Fi, cellular, and Bluetooth configurations to default without affecting your personal data. Samsung also documents checking Settings > Connections on some regional pages when troubleshooting SIM detection. On Android, to manually select a network operator, go to Settings > Connections > Mobile networks > Network operators > Search network > Select manually.

Still not working? When to contact your carrier

If none of the above steps resolve the error, try a different SIM card in your phone. If the second card works, your original SIM is likely faulty and needs replacement. If the problem continues with a different card, the fault is in the device itself. In either case, contact your carrier’s customer support for a replacement SIM or, if the device is at fault, reach out to the manufacturer for repair options.

Frequently Asked Questions

Can a software update fix an invalid SIM error?

On iPhone, Apple specifically directs you to check for a carrier settings update rather than a full iOS update. On Samsung Galaxy devices, the recommended fix is resetting mobile network settings, not a system update.

What should I do if my eSIM shows "No SIM"?

For eSIM devices, the error usually points to a carrier-side issue. Apple advises contacting your carrier directly, as they can re‑provision or troubleshoot the eSIM profile remotely. Do not attempt to remove or re‑insert an eSIM, as it is embedded in the device.

Will a factory reset fix a no SIM error?

Factory resets are not recommended as a first-line fix for this error by either Apple or Samsung. Only consider a factory reset after you have exhausted carrier and manufacturer support.

How can I tell if my SIM card is physically damaged?

Inspect the gold contact area for scratches, chips, or corrosion. If the card is bent or the chip appears cracked, it is likely damaged. Cleaning with a soft, dry cloth may help, but visible damage usually means you need a replacement from your carrier.

For the wider topic, see SIM card information and costs.