On Tuesday, 1st July, Microsoft Teams Classic reached its End of Life (EoL), removing security updates and support for the legacy collaboration platform.
With the deadline now passed, businesses that haven’t transitioned to the new Teams client face significant real-world risks, including operational disruptions and increased cybersecurity vulnerabilities.
EoL events like this often catch organisations off guard. With IT teams juggling numerous priorities, migrations can be delayed until the last minute. But unsupported software presents immediate risks: without future updates or security patches, vulnerabilities can no longer be addressed, leaving companies open to cyber threats and potential compliance failures. And given what we’ve seen so far in 2025, this should be absolutely front of mind to IT leaders.
While many companies may have already upgraded, the Teams Classic deadline serves as a clear warning for what lies ahead with Windows 10’s much wider-reaching EoL in just four months’ time. Organisations that struggled with or delayed their Teams transition may find themselves even more exposed if they don’t get strategic about these 2025 deadlines (and others, ongoing) now. Put simply, modernisation should be an ongoing strategic priority over a last-minute fix.
With that in mind, here are five critical takeaways from the Teams Classic EoL that every IT and business leader should apply before Windows 10 reaches the end of the road:
1. EoL deadlines creep up faster than expected
Many organisations underestimate the time needed for a full upgrade, from auditing systems and securing budgets to testing applications and training staff. The Teams Classic EoL revealed how quickly weeks turn into days when multiple stakeholders are involved. For Windows 10, the scope is far broader – so planning must start now.
2. Legacy systems mean more risk and broken apps
Teams Classic migrations exposed hidden dependencies on outdated plugins, integrations, or hardware. Windows 10 will magnify this challenge as countless applications, drivers, and third-party tools rely on its environment. Ignoring these dependencies risks business-critical apps breaking during or after an upgrade.
3. Communication with end users is key
When users are surprised by sudden changes in their tools, productivity suffers. The Teams EoL should demonstrate that clear, proactive communication – including what’s changing, when, and why – reduces confusion and resistance. For Windows 10, the impact will likely reach every corner of the organisation, making a robust change management plan essential.
4. Compliance can’t be an afterthought
Continuing to run unsupported software exposes organisations to compliance breaches. Teams Classic’s EoL reminded businesses that regulators increasingly expect up-to-date systems as part of cybersecurity strategy. With Windows 10, which underpins the entire enterprise, compliance failures could mean even bigger legal and reputational consequences.
5. Don’t just think migrate, think optimise
Some companies treated the Teams migration as a rushed box-ticking exercise. But successful organisations used it as an opportunity to streamline workflows, remove redundant tools, and modernise policies. The same applies to Windows 10: transitioning to Windows 11 or alternative platforms can enable security, productivity, and management improvements if planned strategically.
What’s next?
Unlike Teams Classic, which affects collaboration for some users, Windows 10 underpins core business infrastructure. As the 14th October 2025 deadline approaches, the potential fallout from leaving upgrades too late is much greater – from cyberattacks on unpatched devices to widespread service outages.
The Teams Classic EoL should be treated as an early warning signal. It highlighted the value of comprehensive audits, strategic planning, end-user engagement, and rigorous testing. Applying those lessons now can ensure organisations approach Windows 10’s withdrawal with confidence, avoiding the last-minute scrambles that create unnecessary cost, disruption, and risk.
About the Author
Jon Dedman is director at Cloudhouse. Jon has been involved in software for over 20 years starting as a developer in the first versions of .NET through leading a development team, into performing business analysis, before moving into pre-sales activities. He has a focused understanding of Governance Risk and Compliance issues, particularly in heavily-regulated industries and working closely with customers to help them achieve the best results from their solutions. He joined Cloudhouse in 2022 to head up the pre-sales activities and provide support across the customer-facing departments. Outside of the office, Jon is interested in anything with an engine and wheels from motor-racing to tinkering with his cars and motorbike.
Featured image: Andreas Prott
