I'm running into the above error when I run the untouched Blazor project.
A lot like this post HTTP Error 500.24 - Internal Server Error : system.web/identity@impersonate is set to true
Difference is there's no "web.config" file. Updating the "web.config" file to having the following piece of code in Core and MVC worked.
<system.web>
<identity impersonate="false"/>
</system.web>
Set system.web/identity/impersonate to false in IIS Manager. See Francesco B's response in following post:
If you do not have a web.config file you can simply add one by
right click the project and click add => new item
and from there select web configuration file and name it web.config
add the following lines in the web.config file
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<system.webServer>
<validation validateIntegratedModeConfiguration="false"/>
</system.webServer>
</configuration>