Exceptions - An unexpected error occurred while starting UiPath Studio

How to troubleshoot UiPath studio throws exception while opening " An unexpected error occurred while starting UiPath Studio" ?

Error message :

     

Approach 1 : Related to Microsoft Security Patch (KB4055002)
Cause:- This is an issue with windows patch KB4055002 which Microsoft has confirmed. This patch has impacted all the WPF applications. Please refer to link https://support.microsoft.com/en-us/help/4074906/typeinitializationexception-or-fileformatexception-error-in-wpf-apps-t
Solution: Manually uninstall this.Net framework update and install the next version. ( January 2018 Monthly Rollup (KB 4074880).)
Here is the step-by-step procedure of re-installing the update:

  1. Access Control Panel
  2. Search for Windows Updates
  3. Under Programs and Features, click the View installed updates link
  4. Search for the KB 4055002 update under the Security and Quality Rollup for Microsoft .NET Framework 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1 section
  5. Select the update and click Uninstall. A confirmation pop-up is displayed
  6. Press Yes in the confirmation window
  7. Restart the computer
  8. Download and install the following components:
  9. Follow the installation steps.
  10. Restart the computer.


Approach 2: In case the above KB is not present in the system, check if there any antivirus/ group policies blocking the access to the files accessed by UiPath Studio for startup

Approach 3
Cause: 
Corruption of file GlobalUserInterface.CompositeFont(part of .NET Framework)

If you check the Studio Logs, you can see the following error  "System.IO.FileFormatException: No FontFamily element found in FontFamilyCollection that matches current OS or greater: Windows7SP1."
Solution:
Run the Fixit Tool for this patch. The Microsoft FixIt tool replaces the corrupt GlobalUserInterface.CompositeFont file from the KB 4055002 with the correct one from the KB 4074906 update.

               The Microsoft FixIt tool for the KB 4074906 update is included in the Windows Update KB 4074906 or it can be downloaded by clicking here.


 

The fix is applied by replacing the corrupt font file with the correct version. If  the fixittool-KB4074906.exe file is run, consider the following:  

  1. Close any running applications.
  2. Run the file from a Command Prompt instance with Administrator privileges.
  3. Run the applications again. The issue is no longer encountered.