Hi we had the same error when installing ArcGIS 10.4.1. Uninstalling 10.3 caused the error. The cause was a reference to a nonexistent drive (D:\). With a USB stick as a substitute drive D:\ work uninstallation. The following command created a log file where the error was found: msiexec / x {9A0BC33A-EAA8-4ED4-8D0C-CB9B42B06D7F} / qb / L * v c: \ temp \ Uninstall.log A search in the text editor to "EsriPy" was a reference to the wrong drive: Log: MSI (s) (B8: 28) [13: 12: 34: 081]: PROPERTY CHANGE: Adding INITIAL_PYDIR property. Its value is 'D:\ EsriPyFld'. Hope it helps
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