Patch Tuesday tracking, breaking-issue coverage, and ongoing reporting on Microsoft 365 and Windows update problems.https://www.errorcodelab.com/enhttps://www.errorcodelab.com/news/patch-tuesday/patch-tuesday-tracker/https://www.errorcodelab.com/news/patch-tuesday/patch-tuesday-tracker/Live tracker for Microsoft's monthly Patch Tuesday: April 2026 KB numbers, confirmed known issues, out-of-band fixes, and what's worth holding back on.patch-tuesdayhttps://www.errorcodelab.com/news/known-issues/secure-boot-certificate-expiration-june-2026/https://www.errorcodelab.com/news/known-issues/secure-boot-certificate-expiration-june-2026/On June 27, 2026, Microsoft's 2011 Secure Boot certificates start expiring. PCs that don't get the 2023 replacements enter a degraded security state. Here's what that means and how to check your machine.known-issueshttps://www.errorcodelab.com/news/known-issues/windows-11-24h2-end-of-updates/https://www.errorcodelab.com/news/known-issues/windows-11-24h2-end-of-updates/Windows 11 24H2 Home and Pro reach end of updates on October 13, 2026. What that actually means, what it does not, and why the staged 25H2 upgrade is the harder story.known-issueshttps://www.errorcodelab.com/news/known-issues/new-outlook-vs-classic-outlook-migration/https://www.errorcodelab.com/news/known-issues/new-outlook-vs-classic-outlook-migration/Microsoft moved the new Outlook opt-out deadline from April 2026 to March 2027. The delay tells you everything about the state of the migration. Here is what is actually missing from the new client and how to plan.known-issueshttps://www.errorcodelab.com/news/known-issues/teams-2x-errors-vs-teams-classic/https://www.errorcodelab.com/news/known-issues/teams-2x-errors-vs-teams-classic/Microsoft retired classic Teams in July 2025. The new Teams 2.x has a different error profile — different cache paths, different sign-in behaviors, different failure modes. Here is what changed and how to triage.known-issues