SumUp Solo not working? Start here

The SumUp Solo is a compact standalone card reader. Unlike the older SumUp Air, it doesn’t need a phone — it’s got its own touchscreen, a built-in SIM for mobile data, WiFi, and a charging cradle. That independence is the selling point, and it also changes how you troubleshoot it.

First move when anything’s off: hold the power button for around 10 seconds to switch the Solo off, wait a moment, then power it back on. A restart clears a surprising number of connection drops, frozen screens and payment errors.

If that doesn’t fix it, find your symptom below.

SumUp Solo not connecting to mobile network or WiFi

The Solo connects through its built-in SIM (free mobile data, no contract from you) and falls back to WiFi. If it can’t reach either, payments won’t go through.

Fix: get the Solo back online

1. Check the signal indicator at the top of the screen. No bars on the SIM means weak mobile coverage where you’re standing — move a few metres, nearer a window or outside, and try again.
2. Switch to WiFi if you have it. In the settings menu, connect to a known WiFi network and re-enter the password carefully.
3. Restart the reader to force it to re-find the network — this clears most “no connection” messages on its own.
4. Indoors with thick walls? The SIM signal can struggle inside stone or metal-clad buildings. WiFi is the more reliable option there.
5. If it still won’t connect after a restart and a signal check, the SIM may need re-provisioning — that’s a support job rather than a hardware fault.

SumUp Solo won’t charge

The Solo charges over USB-C, and optionally sits in a charging cradle. If it’s not charging, it’s nearly always the cable, the socket, or a dirty contact.

Fix: work through the power chain

1. Try the cable direct. Plug the USB-C cable straight into the reader, bypassing the cradle. If it charges this way, the cradle’s the issue.
2. Check the plug and socket. Test the wall socket with another device, and use a proper USB plug — charging from a weak laptop port can be slow or stop entirely.
3. Clean the contacts. If you charge via the cradle, wipe the charging pins on both the reader and cradle. Pocket lint and dust break the connection.
4. Seat it properly in the cradle so the charging indicator appears — sitting in it isn’t the same as charging.
5. Give a flat battery 10–15 minutes before deciding it’s dead. A fully drained Solo can take a while to show any sign of life.

SumUp Solo payment failed or card not reading

If a payment fails, the first question is whether it’s one card or every card — that points you straight at the cause.

Fix: isolate the problem

• One card failing: Ask the customer to insert the chip instead of tapping, or try another card. A worn or blocked card is on them, not the reader.
• Tap not working: Have the customer hold the card flat on the screen for a second longer, or insert the chip instead. Phone wallets sometimes need the screen woken first.
• Every payment failing: Check your connection. A Solo with no signal can’t reach the bank — sort the network (above) and retry.
• Persistent errors after a restart: SumUp’s system may have a temporary outage, or the transaction limit on your account may be involved — worth a check before you blame the hardware.

SumUp Solo won’t turn on

A Solo that won’t power up is usually just flat, even if it looked fine when you put it away.

• Put it on charge first and leave it 15 minutes before trying again — a deeply flat battery won’t respond to the power button straight away.
• Watch for the charging light coming on once plugged in. No light at all points back to the cable, plug or socket — work through those.
• Hold the power button for a full 15 seconds once it’s had some charge. A short press won’t wake a reader that’s fully drained.
• If there’s still nothing after a proper charge and a long press, that’s the point to contact support rather than keep trying.

SumUp Solo stuck updating

The Solo updates its software over the air now and then. If it stalls on an update screen, don’t yank the power.

• Give it time — updates can take several minutes. A moving progress bar is fine; leave it alone.
• Keep it online and charged. Plug it in and stay on a stable connection so the update can finish cleanly.
• If it’s genuinely frozen for 20+ minutes with no movement, hold the power button to restart — it should pick the update back up or roll it back.
• Don’t keep force-restarting. If one reboot doesn’t recover it, contact support rather than cycling the power repeatedly.

Frequently Asked Questions

Why is my SumUp Solo not working?

A SumUp Solo not working usually comes down to a weak mobile signal where you’re trading, a flat battery, or a reader that needs a restart. Because the Solo has its own built-in SIM and WiFi, a “no connection” message almost always means poor signal rather than a broken device. Restart the reader, check the signal indicator, and connect to WiFi if the SIM is struggling — that clears most faults.

How do I restart a SumUp Solo?

Hold the power button for around 10–15 seconds until the reader switches off, wait a few seconds, then power it back on. A restart fixes frozen screens, dropped connections and most payment errors. There’s no need for a factory reset in normal use — only do that if SumUp support asks you to.

Why won’t my SumUp Solo connect?

The Solo connects through a built-in SIM and falls back to WiFi. If it won’t connect, you’re most likely in a spot with weak mobile signal — move nearer a window or outside, or connect to a WiFi network in the settings menu. A quick restart forces the reader to re-find the network and clears most “no connection” messages.

Does Smart Payment Solutions supply the SumUp Solo?

Yes — we supply and support SumUp readers including the Solo, alongside Square, Teya, Shift4, Clover and others. As an independent broker we’re not tied to one provider, so we’ll match you to the reader or machine that genuinely fits how you trade, with no long contracts and a freephone line if you need a hand.

Still not sorted? Here’s the next step

If you’ve worked through these and the Solo still won’t behave, it’s worth weighing up whether it’s the right device for how you trade. A reader that loses signal at your pitch, or fees that have crept up, can cost you more in missed sales than the hardware’s worth.

We’re based in the North East and have helped over 500 UK businesses get their card payments right — the proper machine for the job, fair rates, and support you can actually phone. No long contracts on anything we recommend, and no pressure if your current setup’s working fine.

Want a second opinion? Request a no-obligation quote or give us a ring and we’ll give you a straight answer.