Object reference not set to an instance of an object

Yesterday I found a solution for this error message, but maybe it will work only in some cases.

I use Windows 10, and yesterday I did the Power BI upgrade to the July release (Versión: 2.48.4792.721 64-bit (julio de 2017)). After restarting, Power BI didn't open, kept running the starting window during 5 minutes, and finally opened a window with the error message "Object reference not set to an instance of an object". After closing the error message, it kept running the starting window, but never open.

In our company there's a proxy server and security rules that modify the configuration of proxy exceptions. Recently, TI department modified the rules and added the exception "*powerbi.com*;" in the field "Do not use proxy server for addresses beginning with:". I deleted the text *powerbi.com* from the exception field, and the problem was solved.

I don't know if this can solve all the instances of the error, but in my case it works.