eSIM Not Activating? Fix Common Issues

Why Is My eSIM Not Activating in the UK?

The three most common reasons an eSIM fails to activate in the UK are: your phone is carrier-locked to another network, the QR code has already been used (each code is single-use), or your phone lost its Wi-Fi connection mid-activation. This guide walks you through every common eSIM failure — from 'activation failed' errors to greyed-out settings — with step-by-step fixes for iPhone, Samsung Galaxy, and Google Pixel.

Whether you've just scanned a Fuse QR code or you're troubleshooting an eSIM that's gone quiet after an update, you'll find the fix here.

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Problem 1: QR Code Scanned but 'Activation Failed'

This is the most frequent eSIM issue. You scan the QR code, your phone thinks for a moment, then throws an error. Here's why it happens and how to fix it.

Common Causes

• The QR code has already been scanned (each eSIM QR code is single-use)
• Your phone is still carrier-locked to a previous network
• Your Wi-Fi dropped during the activation process

The Fix

1. Check your Wi-Fi connection first. eSIM activation requires a stable internet connection — mobile data won't work because you're in the middle of downloading the eSIM profile. Connect to a reliable Wi-Fi network, not a public hotspot if you can avoid it.

2. Confirm the QR code hasn't been used. If you scanned it once and it failed, the code may now be invalid. Contact your provider — for Fuse customers, head to Fuse Help and the support team can issue a fresh activation code.

3. Verify your phone is unlocked. Dial *#06# to find your IMEI, then check with your previous carrier whether the phone is unlocked. If it's still locked, you'll need to request an unlock before any eSIM from another provider will activate.

Tip: If you're activating a Fuse eSIM, you can also log in to the Fuse app to manage your eSIM profile and request a new QR code if yours has expired.

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Problem 2: eSIM Downloaded but Showing 'No Service'

Your phone accepted the eSIM profile — it appears in your settings — but you're getting 'No Service' or 'Searching' where signal bars should be.

Common Causes

• The eSIM profile downloaded but wasn't set as your active line
• APN settings weren't configured automatically
• The eSIM plan hasn't been activated on the provider's side yet

The Fix

On iPhone:

1. Go to Settings → Mobile Service (or Cellular on older iOS versions)
2. Tap the eSIM line and make sure Turn On This Line is toggled on
3. Under Mobile Data, select your eSIM line as the data source

On Samsung Galaxy:

1. Open Settings → Connections → SIM Manager
2. Tap your eSIM and toggle it Active
3. Under Mobile Data, select the eSIM as your preferred data SIM

On Google Pixel:

1. Go to Settings → Network & Internet → SIMs
2. Tap your eSIM and enable it
3. Set it as your Preferred SIM for mobile data

If the line is active but still showing no service, wait up to five minutes — network registration can take a moment. If it persists beyond that, move on to the APN fix below.

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Problem 3: eSIM Greyed Out in Settings

You go to add an eSIM and the option is completely greyed out or missing. This is almost always a carrier-lock issue.

Common Causes

• Your handset is locked to your previous UK carrier
• You're running an older iOS or Android version that has a known eSIM bug
• Your device doesn't support eSIM (less common on modern phones)

The Fix

1. Check your device is eSIM-compatible. Most phones released after 2018 support eSIM, but budget handsets sometimes don't. Check your manufacturer's spec page to confirm.

2. Request an unlock from your current carrier. In the UK, carriers are legally required to unlock your phone for free once your contract is complete (and many will do it mid-contract for a small fee or for free). Contact them by phone or online chat — unlocking typically takes 24–72 hours.

3. Update your software. Go to Settings → General → Software Update (iPhone) or Settings → Software Update (Android). eSIM support improved significantly in iOS 16+ and Android 12+. Running outdated software can cause the eSIM menu to disappear entirely.

Warning: Don't attempt to use third-party unlocking services. These can void your warranty and sometimes permanently damage the baseband software.

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Problem 4: Data Not Working After Activation

Your eSIM shows a signal, calls might even work, but mobile data refuses to connect. This is almost always an APN configuration problem.

What Is an APN?

APN stands for Access Point Name — it's the gateway setting that tells your phone how to connect to your carrier's data network. Most eSIMs configure this automatically, but it occasionally needs to be set manually.

The Fix

On iPhone:

1. Go to Settings → Mobile Service → Mobile Data Network (you may need to scroll down)
2. Under Mobile Data, enter the APN details provided by your carrier
3. For Fuse customers, your APN details are available in the Fuse app under Account → eSIM Settings
4. Restart your phone after saving

On Samsung Galaxy:

1. Go to Settings → Connections → Mobile Networks → Access Point Names
2. Tap the + icon to add a new APN
3. Enter your carrier's APN details and tap Save
4. Select the new APN from the list

On Google Pixel:

1. Go to Settings → Network & Internet → SIMs → [Your eSIM]
2. Tap Access Point Names → Add
3. Enter the APN details and save

Tip: After changing APN settings, toggle Aeroplane Mode on for 10 seconds, then off again. This forces your phone to re-register on the network with the new settings.

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Problem 5: eSIM Disappeared After a Factory Reset or iOS Update

eSIM profiles are stored on your device's eUICC chip — but a factory reset wipes them. An iOS or Android update can occasionally cause the profile to become unreadable too.

The Fix

1. Don't panic — your plan is still active on the provider's side. The eSIM profile just needs to be re-downloaded to your device.

2. Request a new QR code from your provider. For Fuse customers, visit Fuse Help or log in to the Fuse app. Support can issue a fresh QR code tied to your existing plan — your data allowance and billing cycle won't be affected.

3. Re-scan and activate. Once you have the new QR code, follow the standard installation steps for your device (see the device-specific sections below). Make sure you're on Wi-Fi before scanning.

Important: If you're upgrading to a new iPhone, use the Transfer from iPhone option in iOS Setup Assistant — this can migrate your eSIM profile directly without needing a new QR code. This works for iPhone 12 and later running iOS 16+.

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Problem 6: 'Could Not Activate Mobile Data' on iPhone

This specific error message on iPhone usually means one of three things: the eSIM profile is corrupted, the line isn't set as the mobile data source, or there's a temporary network registration issue.

The Fix

1. Set your eSIM as the mobile data line. Go to Settings → Mobile Service → Mobile Data and select your eSIM. If you have two lines (a physical SIM and an eSIM), iPhones sometimes default to the physical SIM for data.

2. Remove and re-add the eSIM profile. Go to Settings → Mobile Service, tap your eSIM line, scroll down and tap Remove Mobile Plan. Then re-scan your QR code to reinstall it. You'll need a new QR code if the original has already been used — contact Fuse Help if you need one.

3. Reset network settings. Go to Settings → General → Transfer or Reset iPhone → Reset → Reset Network Settings. This clears saved Wi-Fi passwords too, so note those down first. After resetting, re-add your eSIM.

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Device-Specific eSIM Installation Steps

iPhone (iOS 17 and Later)

1. Go to Settings → Mobile Service → Add eSIM
2. Tap Use QR Code and scan your activation QR code
3. Tap Continue through the confirmation screens
4. Once downloaded, go to Mobile Data and select your new eSIM line
5. Toggle Data Roaming on if you're travelling abroad

Samsung Galaxy S24 / S25

1. Open Settings → Connections → SIM Manager → Add Mobile Plan
2. Tap Scan Carrier QR Code
3. Scan your QR code and follow the on-screen prompts
4. Once installed, go to SIM Manager and set the eSIM as your active data SIM
5. Restart your phone to complete registration

Google Pixel 8 / 9

1. Go to Settings → Network & Internet → SIMs → Add SIM
2. Tap Download a SIM instead? if prompted, or select Scan QR code
3. Scan your activation QR code
4. Follow the prompts to confirm and activate
5. Set the new eSIM as your preferred mobile data SIM under SIM preferences

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Why Fuse eSIM Activation Is Designed to Be Straightforward

Fuse's eSIM works across all four UK networks — EE, Three, Vodafone, and O2 — so your phone automatically connects to whichever signal is strongest at any given moment. That multi-network design means fewer dead zones and fewer 'No Service' moments compared to a single-network eSIM.

Activation takes about two minutes via QR code, and if anything goes wrong, the Fuse app gives you direct access to your eSIM profile and support. You can also start with a 7-day free trial — 500MB included — to make sure everything works before committing to a plan. Learn more about how Fuse works.

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Frequently Asked Questions

Why does my eSIM say 'No Service' after activation?

The most likely cause is that the eSIM line isn't set as your active mobile data source. Go to your SIM settings and confirm the eSIM is both enabled and selected for mobile data. If the line is active but still shows no service, check that your APN settings are correct — your provider should supply these.

Can I reuse an eSIM QR code if activation failed?

No — eSIM QR codes are single-use for security reasons. If your activation failed and the QR code has already been scanned, contact your provider for a replacement code. Fuse customers can request one via Fuse Help.

Why is the eSIM option greyed out on my phone?

This almost always means your handset is carrier-locked. Contact your previous network to request an unlock — UK carriers must unlock devices for free once the contract period is complete. Some will do it earlier on request. Allow 24–72 hours for the unlock to process.

Will a factory reset delete my eSIM?

Yes. A factory reset wipes the eSIM profile stored on your device. Your plan remains active on the provider's side, so you just need a new QR code to re-download the profile. Contact your provider to get one.

My eSIM shows signal but I can't use data — what's wrong?

This is typically an APN configuration issue. Your phone has registered on the network but doesn't have the correct settings to route data traffic. Check your provider's APN details and enter them manually under your mobile network settings, then toggle Aeroplane Mode off and on to refresh the connection.

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Summary

eSIM activation problems in the UK usually come down to a handful of fixable issues: a carrier-locked handset, a used QR code, a dropped Wi-Fi connection during setup, or a misconfigured APN. Working through them in order — unlock status first, then connectivity, then APN — resolves the vast majority of cases.

If you've tried everything here and you're still stuck, the Fuse support team is on hand at Fuse Help. And if you're yet to try Fuse, a 7-day free trial costs nothing and gets you connected to all four UK networks in minutes.