eSIM Not Working in Japan? Complete Troubleshooting Guide

60-Second Fix: Try This First

Before going through the full guide, do these three things — they fix 90% of eSIM issues:

1. Turn on Data Roaming for your Japan eSIM (Settings > Cellular/SIMs > [Japan eSIM] > Data Roaming > ON)

2. Set Japan eSIM as your data line (Settings > Cellular/SIMs > Cellular Data > select Japan eSIM)

3. Toggle Airplane Mode on, wait 10 seconds, toggle off

Still not working? Read on.

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No Signal / "No Service"

This is the most common problem. Work through these fixes in order:

1. Verify Data Roaming Is ON

The #1 cause. Your phone blocks data by default on eSIMs because it considers them "roaming" — even though you're using a Japan-local plan.

iPhone: Settings > Cellular > [Japan eSIM] > Data Roaming > ON

Android: Settings > Network & Internet > SIMs > [Japan eSIM] > Roaming > ON

"Data Roaming" won't charge you extra fees. It's just a toggle that allows data on this SIM.

2. Check Your Data Line Selection

Your phone might be routing data through your home SIM instead.

iPhone: Settings > Cellular > Cellular Data > select the Japan eSIM

Android: Settings > SIMs > [Japan eSIM] > turn on Mobile Data

3. Restart Your Phone

Power off completely. Wait 10 seconds. Power on. This resets the network stack and forces a fresh network registration.

4. Manual Network Selection

If automatic selection isn't finding a network:

iPhone: Settings > Cellular > [Japan eSIM] > Network Selection > turn OFF Automatic > wait > select a network

Android: Settings > Network & Internet > SIMs > [Japan eSIM] > Network operators > Search manually

Select the network matching your provider:

5. Check APN Settings

Some providers require specific APN (Access Point Name) settings. Check the email or app from your provider for APN instructions. If provided:

iPhone: Settings > Cellular > [Japan eSIM] > Cellular Data Network > enter APN

Android: Settings > Network & Internet > SIMs > [Japan eSIM] > Access Point Names > add new APN

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Can't Install or Activate eSIM

"eSIM Cannot Be Added" Error

Carrier lock: Your phone may be locked. Contact your home carrier to request an unlock. This is separate from your phone being "paid off."

eSIM storage full: iPhones store up to 8-10 eSIMs. Delete old ones: Settings > Cellular > [old eSIM] > Remove Cellular Plan.

Already used QR code: Most eSIM QR codes are single-use. If you deleted the eSIM after scanning, contact your provider for a new code.

QR Code Won't Scan

• You need an active internet connection (WiFi or mobile data) to download the eSIM profile
• Try in better lighting — the camera needs to read the QR clearly
• Use manual entry: enter the SM-DP+ address and activation code (found in your provider's email or app)

"No Connection" During Installation

The eSIM download requires internet. If you're at the airport without WiFi:

• Connect to free airport WiFi first (available at Narita, Haneda, Kansai)
• Or use your home carrier's data briefly to complete the download

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Connected But Slow

Check Data Balance

You may have hit your data cap. Most plans throttle to 128 kbps instead of cutting off completely. Check remaining data in your provider's app.

If depleted:

• Buy a top-up through the provider's app (Airalo, Ubigi support this)
• Or purchase a new plan — Compare plans

Daily Throttling on "Unlimited" Plans

Some "unlimited" plans have a daily high-speed cap (typically 1-3 GB/day). After exceeding it, speeds drop to 1-3 Mbps until midnight Japan time (JST).

Disable VPN and Private Relay

VPNs add latency and can conflict with eSIM APNs.

iPhone: Also disable iCloud Private Relay: Settings > [your name] > iCloud > Private Relay > OFF

Network Congestion

Speeds drop in extremely crowded areas (Shibuya Crossing, festivals, major events). This affects all carriers. Moving one block away usually restores speeds.

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Connection Drops Intermittently

Underground and Tunnels

Brief drops in subway tunnels and deep underground stations are normal. Most Tokyo Metro and JR stations have coverage on platforms but not between stations. Connection restores within seconds of surfacing.

Rural Areas

Rural coverage varies by carrier, roaming agreement, device, and exact location. Check the provider's current Japan network and the carrier coverage map for your route; Ubigi is one option whose network must also be confirmed for the selected plan.

For detailed coverage by area, see our Japan coverage guide.

Shinkansen

The bullet train maintains signal for most routes with brief drops in tunnels. This is normal and unavoidable.

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iPhone-Specific Issues

eSIM Disappeared After iOS Update

Rare but happens. Go to Settings > Cellular — if the eSIM shows but is disabled, toggle it on. If it's completely gone, contact your provider for a reinstall.

"SIM Failure" Message

• Restart your iPhone
• Remove and re-add the eSIM (only if you have the original QR code or can get a new one)
• Reset network settings: Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings (this will forget saved WiFi passwords)

Dual SIM Conflicts

If you're using both your home SIM and Japan eSIM:

• Make sure the Japan eSIM is set for Cellular Data
• Your home SIM can stay active for calls/texts
• Turn off "Allow Cellular Data Switching" to prevent your phone from using your expensive home data: Settings > Cellular > Cellular Data > turn off Allow Cellular Data Switching

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Android-Specific Issues

Samsung: eSIM Option Missing

On some Samsung phones, eSIM may be hidden if the phone is carrier-locked. Contact your carrier to unlock, then check Settings > Connections > SIM Manager.

Pixel: "Can't Connect to This Network"

• Try Settings > Network & Internet > SIMs > [Japan eSIM] > tap the gear icon > Access Point Names > verify APN settings
• Reset network settings: Settings > System > Reset options > Reset WiFi, mobile & Bluetooth

Multiple eSIM Conflicts

If you have multiple eSIMs installed, only one data eSIM can be active at a time. Disable other eSIM data connections and set the Japan eSIM as primary.

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Emergency Fallbacks

If your eSIM absolutely won't work, you still have options:

1. Free WiFi — Available at airports, JR stations, convenience stores (7-Eleven, FamilyMart, Lawson), Starbucks, and most hotels

2. Buy a physical SIM at the airport — Available at vending machines at Narita and Haneda

3. Rent a Pocket WiFi — Available at airport counters (book in advance if possible)

4. Emergency calls — 110 (police) and 119 (ambulance) work on any network, even without an active plan

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Prevention Checklist

Set up correctly before you fly to avoid problems:

Install the eSIM 1-2 days before departure (on WiFi at home)

Turn on Data Roaming immediately after install

Set it as your data line (but don't activate until arrival)

Download offline Google Maps for Japan as backup

Save your provider's support contact info offline

Screenshot your QR code and activation details

Full pre-trip checklist

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Provider Support Contacts

Related Guides

• Set Up eSIM on iPhone — Step-by-step setup
• Set Up eSIM on Android — Samsung, Pixel, and more
• Is My Phone Compatible? — Device compatibility list
• Japan Network Coverage Guide — Which networks work where
• Compare eSIM Plans — Find a plan that works for you