500 Errors - not displaying detailed error

Edit the web.config file in your DOMAIN/wwwroot folder

Scroll down and find (the very last lines)

</handlers>
</system.webServer>
</configuration>

after </handlers> press enter and add the following line

<httpErrors errorMode="Detailed"/>

it should now look like:

</handlers>
<httpErrors errorMode="Detailed"/>
</system.webServer>
</configuration>

save this file, this will now show 500 errors.