TeamViewer recommends that all users download and start using the latest version of TeamViewer on all supported operating system platforms.
When you see a pop-up offering you to Update Now, please check the version of the TeamViewer (Classic) software you are currently using, and immediately update to the latest version of TeamViewer.
This article applies to all TeamViewer (Classic) users who have not upgraded the TeamViewer (Classic) software to the latest version and see the error message: "Unable to connect - Reason unknown".
Check TeamViewer (Classic) version
- Windows: TeamViewer (Classic) ➜ Help ➜ About TeamViewer ➜ Version
- macOS: TeamViewer (Classic) ➜ About TeamViewer ➜ Version
- Linux: TeamViewer (Classic) ➜ Help ➜ About TeamViewer ➜ Version
- Android: TeamViewer (Classic) ➜ Settings ➜ Version
- iOS: TeamViewer (Classic) ➜ Settings ➜ Advanced Settings ➜ Version Information
At the same time, please check the compatibility of operating systems and software versions: Supported operating systems.
Solution
When you see the error messages in TeamViewer (Classic) with Reason Unknown, and the connection cannot be established, please download and update TeamViewer to the latest version.
Windows, Linux and macOS
When the TeamViewer (Classic) software pops up with an error: Unable to connect - Reason unknown, please update TeamViewer to the latest available version.
- On the TeamViewer (Classic) software, click Help ➔ Check for new version to complete the software update
- Download the latest version of TeamViewer
Mobile devices - Android and iOS
When the TeamViewer remote control app shows the following error:
Android: Could not connect to partner
iOS: Unable to connect - A connection could not be established. Reason unknown
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