Reloading the cache is has nothing to do with this exception. This exception is a security exception. Your server code tried to do something it did not have permissions to do.
Instead of enabling tracing, turn off CustomErrors in web.config instead. When the ASP.NET code crashes it will display an error page with the details.
<system.web>
<customerrors mode="Off" />
...
</system.web>
Without further information, it's impossible to tell you how to fix this.