"TypeInitializationException" or "FileFormatException" error because of windows patch KB4055002

Issue : UiPath studio fails to load with error message - “An unexpected error occurred while starting UiPath Studio. Unfortunately it needs to be closed.”

Error message in Studio logs - "An unexpected error occurred, shutting down the application | [TargetInvocationException] System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. —> System.Windows.Markup.XamlParseException: The invocation of the constructor on type ‘ActiproSoftware.Windows.Controls.Ribbon.Ribbon’ that matches the specified binding constraints threw an exception. —> System.TypeInitializationException: The type initializer for ‘ActiproSoftware.Windows.Controls.Ribbon.Ribbon’ threw an exception. —> System.TypeInitializationException: The type initializer for ‘System.Windows.Media.Fonts’ threw an exception. —> System.IO.FileFormatException: No FontFamily element found in FontFamilyCollection that matches current OS or greater: Windows7SP1 —> System.IO.FileFormatException: No FontFamily element found in FontFamilyCollection that matches current OS or greater: "

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Solution - This is an issue with windows patch KB4055002 which Microsoft has confirmed. This patch has impacted all the WPF applications. Please refer to link "TypeInitializationException" or "FileFormatException" error in WPF applications that request fallback fonts after you install the January 9, 2018, .NET Security and Quality Rollup (KB4055002)

for more insight about the issue and solution.

Thank you.:slight_smile: