As of today, Microsoft Teams Classic is no longer operational.
The legacy app has officially been decommissioned, with all backend services disabled, all servers shut down.
For IT teams globally, this isn’t just a routine product retirement, it's a wake-up call.
The death of Classic Teams arrives just months before another major deadline: the end of Windows 10 support in October 2025.
Together, these two shifts represent a pivotal moment for IT leaders that should force a reassessment of short-term fixes and long-term resilience.
Delayed Migrations, Compressed Timelines
Despite Microsoft flagging the end of Teams Classic more than a year ago, many organisations waited until the last possible minute to make the switch.
Some leaned on Extended Security Updates (ESUs). Others fast-tracked hardware refresh cycles. But rushed rollouts come at a cost, with user disruption, increased support tickets, and teams stretched to the brink.
Even worse, a reactive approach leaves little room to test, document, or train properly – all while the clock ticks toward the Windows 10 deadline.
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Security Risks of Legacy Systems Are Escalating
The risks tied to outdated platforms have become even more evident in the last six months.
A recent study from the UK's Royal Institution of Chartered Surveyors found that over a quarter of UK businesses fell victim to cyberattacks over the past year.
What’s more alarming is that nearly three-quarters of business leaders anticipate their organisations will face cybersecurity disruptions within the next one to two years.
This widespread apprehension reflects the very real dangers posed by running outdated software.
With Teams Classic now completely unsupported, any lingering use opens the door to serious vulnerabilities – from data leaks and infrastructure weaknesses to damaging impacts on brand reputation.
Without vendor patches or official support, any newly discovered flaws remain unaddressed, making systems an easy target for malicious actors.
Windows 10 End-of-Life: The Next Major Challenge
For many IT leaders, Teams Classic is only the first hurdle – October 14, 2025 marks the end of support for Windows 10.
While Microsoft will continue offering paid ESUs to provide additional security patches, these are expensive temporary fixes, not substitutes for a full migration.
