Windows 11 Upgrade: What UK Businesses Must Do Now Windows 10 Support Has Ended
Windows 10 stopped receiving security updates on 14 October 2025. That was almost a year ago, and a surprising number of UK businesses are still running it. Not because anyone decided to, but because the upgrade was a project nobody owned, the machines still switch on every morning, and nothing has visibly gone wrong yet. That last part is the dangerous bit. An unpatched operating system does not fail loudly. It just quietly stops being defensible.
The short version
- Windows 10 is out of support. No security patches, no fixes, regardless of how well the machine runs.
- Extended Security Updates buy time, not safety. They are paid, they escalate in price each year, and they end in October 2028.
- Roughly half of a typical ageing fleet cannot take Windows 11 because of TPM 2.0, Secure Boot and processor requirements.
- Check the hardware before you budget. The upgrade cost is not licensing, it is the machines that need replacing.
- Your insurer and your clients may already care. Unsupported operating systems are a common exclusion and a common question in supplier security reviews.
What "end of support" actually means
It does not mean your computers stop working. It means Microsoft no longer issues security updates for Windows 10, so every vulnerability discovered from October 2025 onward stays open on those machines permanently. Attackers know the dates as well as anyone, and unpatched, widely deployed software is the cheapest target there is. The gap does not stay the same size either. It widens every month.
The practical risk is not that someone targets your business specifically. It is that automated scanning finds a known, unpatched weakness and nobody has to work very hard after that.
Extended Security Updates: useful, but understand what you are buying
Microsoft offers paid Extended Security Updates for commercial customers, running in one-year blocks through to October 2028. They deliver critical and important security patches only. No features, no bug fixes, no new functionality.
Two things catch businesses out. First, the price is per device and roughly doubles with each year you stay on it, so a fleet you meant to migrate "next year" gets more expensive to postpone every time. Second, ESU covers the operating system. It does not oblige anyone else to support you: application vendors, security tooling and hardware manufacturers drop unsupported platforms on their own timetables.
ESU is a bridge for a migration that is genuinely already underway. It is a poor substitute for one that has not started.
Why some machines simply cannot upgrade
Windows 11 has hardware requirements that Windows 10 did not, and they are not negotiable in any supportable way:
- TPM 2.0, a security chip that many machines built before roughly 2018 either lack or have disabled in firmware.
- Secure Boot enabled, which requires UEFI rather than legacy BIOS.
- An approved processor, broadly Intel 8th generation or newer and AMD Ryzen 2000 or newer.
- 4GB RAM and 64GB storage as an absolute floor, though anything you would actually want to work on needs considerably more.
There are unofficial workarounds that force the installation. We do not recommend them for business machines. Microsoft has been explicit that unsupported installs may not receive updates, which puts you back exactly where you started, only with less warning.
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Work out what you actually have
Before anyone talks about budget, you need an accurate inventory: every machine, its Windows version, its processor, whether TPM 2.0 is present and enabled, and how old it is. Guessing produces two expensive mistakes, replacing machines that were fine and discovering mid-project that a department cannot upgrade at all.
Most businesses find their fleet splits three ways. Some machines upgrade in place with no hardware change. Some need a firmware setting turned on, TPM or Secure Boot that was simply never enabled, and then upgrade fine. The rest need replacing. That third group is your real budget, and its size is the single number worth establishing first.
A sensible order to do this in
- Inventory everything and sort it into upgradeable, fixable in firmware, and needs replacing.
- Deal with the firmware group first. It is usually the cheapest win and it shrinks the replacement list.
- Test your line-of-business applications on Windows 11 before you migrate anyone who depends on them. Older accounting, CAD and industry-specific software is where problems surface.
- Migrate in waves, starting with a small pilot group who will tell you honestly what broke.
- Replace the remainder on a schedule you control, spreading the cost across quarters rather than absorbing it in one hit.
Done this way the work is unremarkable. Done as an emergency after an incident or a failed audit, it is expensive and disruptive at the same time.
The commercial reasons this is now urgent
Security aside, unsupported operating systems increasingly show up where they cost you money. Cyber insurance applications ask whether your systems are supported and patched, and an inaccurate answer can affect a claim. Cyber Essentials certification requires supported, patched software, so a Windows 10 estate will fail. Larger clients running supplier security reviews ask the same question, and increasingly they ask for evidence rather than a tick.
If you sell to enterprise, government or regulated sectors, this stops being an IT decision and becomes a sales one.
What we would do
If this is sitting on your list untouched, the first step is small: get an accurate picture of the fleet. That is a couple of hours of work and it turns a vague worry into a specific number you can plan around. From there most businesses migrate over a few months without drama.
We handle Windows 11 migrations for London businesses, from the initial audit through to replacing what needs replacing and moving people across without losing a day's work. If you would like the audit done properly, call 0207 112 4812 or book ad-hoc support here. Our rate is £50 per hour plus VAT and we will tell you honestly if the job is smaller than you feared.
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