Consider the following scenario: Developing with debug compilation and using IIS Express. Everything works fine without license. Episerver allows development under those circumstances.
But if you deploy to a new IIS site or even to Azure web app and you set compilation without debug, because you probably published with Release configuration:
<system.web>
<httpRuntime targetFramework="4.7.2" requestValidationMode="2.0" fcnMode="Single" />
<compilation targetFramework="4.7.2" optimizeCompilations="true" debug="false"/>
The site will show up with this error:

If you change the compilation for debug
<system.web>
<httpRuntime targetFramework="4.7.2" requestValidationMode="2.0" fcnMode="Single" />
<compilation targetFramework="4.7.2" optimizeCompilations="true" debug="true" />

Now you get the site, but with the episerver warning stating that license does not exists.
Add the license.config file to root of the site or to another folder and update the file EPiServerFramework.config with:
<licensing licenseFilePath="License.config" />
</episerver.framework>
Refresh the site and is back to work:
