Forum Discussion
Teams build 25275.2601.4002.2815) instantly closes on launch ucrtbase.dll error 0xc0000409
After updating to Teams 25275.2601.4002.2815, the app opens for one second then closes—no UI, no error. Env: Win 11 Pro 23H2 (26100) WebView2 141.0.3537.92 Entra ID joined (AAD) Faulting module:...
This is a clear-cut case of a flawed Teams update.
Your diagnostic work is correct the crash points to a coding error in build 25275, not your PC.
Stop troubleshooting; the fault lies entirely with Microsoft's software.
Please report this via Feedback Hub with your details.
The only reliable fix is to uninstall this version and reinstall the older, working August/September build.
A rollback is your path to productivity until Microsoft provides a patch