Microsoft Teams ‘Connection Failed’ Error After Recent Sidebar Update – Solution Available
Microsoft is currently addressing a service degradation issue affecting Microsoft Teams users worldwide, which results in a “couldn’t connect to this app” error when launching the desktop and web applications. This problem, tracked under Microsoft reference TM1131505, originated from a recent update aimed at enhancing the platform’s user interface. Users began reporting the issue on August 8, 2025, encountering an error message that hinders the application from loading correctly. Although disruptive, Microsoft has provided a straightforward workaround, allowing users to bypass the error screen by clicking on the “Activity” or “Chat” icons in the left-hand navigation sidebar. This action successfully loads the application, restoring access to all functionalities. An investigation revealed that the root cause was an unoptimised code flow introduced by the recent sidebar update, affecting a wide range of users across various organisations.
As of August 19, 2025, Microsoft announced that the deployment of a corrective patch is well underway, with approximately 25% of the global infrastructure having received the fix. The company is optimistic that the deployment will be completed and the issue fully resolved by the next scheduled communication. This incident is classified as a service degradation, meaning the core service remains operational despite the disruptive bug. Importantly, this is not a security-related incident, and user data remains secure. The issue is limited to the initial loading sequence of the Teams desktop and web clients. Microsoft has assured customers that it is working diligently to resolve the problem, with the next formal update expected by Thursday, August 21, 2025, at 6:30 PM UTC. In the meantime, users experiencing the “couldn’t connect” error are encouraged to utilise the sidebar-click workaround to access their Teams environment.
Categories: Service Degradation, Software Update Issues, Security Vulnerabilities
Tags: Microsoft, Teams, Service, Degradation, Error, Update, Workaround, Code, Vulnerability, Patch