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Microsoft connectivity test tool triggers security warnings due to expired certificate

Feeds.4Sysops •IT News • June 16, 2026

Microsoft has failed to renew the SSL/TLS certificate for connectivity.office.com, a domain used by IT professionals to verify network access to cloud services. Visitors to the site are currently encountering untrusted connection warnings in their web browsers because the certificate expired on June 14. This specific tool is essential for testing firewall configurations and ensuring that organizational traffic can reach Microsoft 365 servers without interference. Source

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Microsoft Connectivity Domain Faces Trust Issues After Certificate Expiry Microsoft's connectivity.office.com domain, used by IT professionals to test access to Microsoft 365, began displaying untrusted connection warnings after its TLS certificate expired on June 14, 2026. The certificate had not been renewed for over 35 hours at the time of reporting, raising concerns about Microsoft's certificate management practices. The expired certificate resulted in NET::ERR_CERT_DATE_INVALID errors, affecting users attempting to validate network access. Although the situation is irritating for users, it is not catastrophic compared to potential issues with critical services like login.microsoft.com. Microsoft has been contacted for a response but had not provided one by the time of publication. The incident highlights the importance of timely certificate renewals, especially as SSL/TLS certificate lifespans are set to decrease in the coming years. 5 sources 37

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Domains (1)

connectivity.office.com