Microsoft Teams “Couldn’t Connect” Issue After Sidebar Update Gets a Fix

Microsoft is addressing a widespread service disruption affecting its Teams collaboration platform, which began on August 8, 2025. Users globally reported encountering a 'couldn't connect to this app' error when attempting to launch either the desktop or web versions of Teams. This issue, tracked under Microsoft reference TM1131505, originated from a recent interface enhancement update that inadvertently introduced instability into the application. According to a service health notification from Microsoft, the changes made to the left sidebar interface enabled 'an unoptimized code flow' that triggers connection failures during the application's initialization process. Despite the disruption, Microsoft confirmed that core functionalities of Teams remain intact, classifying the issue as service degradation rather than a complete outage. Importantly, the company stated that user data remains fully protected throughout this disruption, with no associated security risks reported. Microsoft is actively deploying a fix, with updates expected to be released shortly after the initial reports. Users are encouraged to monitor the official service health notifications for further updates and guidance. The technical investigation into the issue revealed that the modifications made to the interface, while aimed at enhancing user experience, led to unexpected bugs that affected the application's startup process. Microsoft has assured users that it is prioritizing the resolution of the problem and is committed to restoring normal functionality as quickly as possible. The company has been transparent about the ongoing technical challenges and is working closely with affected users to address their concerns. As the situation develops, Microsoft is expected to provide regular updates on the status of the fix and any additional steps users may need to take. In the meantime, users experiencing the connectivity issues are advised to check their internet connections and ensure that they are using the latest version of the Teams application. Further recommendations from Microsoft will be communicated through official channels as the situation progresses.