It is not really a "Mendix" known issue as it is IIS related technically. But yes, Mx7 introduced a file called metamodel.json and IIS does not handle .json files by default. So you need to do this (see the accepted answer): https://stackoverflow.com/questions/22951046/404-not-found-when-i-look-for-json-file-in-asp-net-mvc-app
I will ask our technical writers to update our documentation here: https://docs.mendix.com/deployment/on-premises/deploy-mendix-on-microsoft-windows
Update
The documentation has been updated -> https://docs.mendix.com/deployment/on-premises/deploy-mendix-on-microsoft-windows#5-3-configuring-the-mime-types
This is a known issue. 7.13.1 doesn't load the license properly.
I suggest you raise a ticket at Mendix support
It has to be possible to reach metamodel.json from external. Is this possible?
This is my current web.config:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<rewrite>
<rules>
<rule name="xas" enabled="true" stopProcessing="true">
<match url="^(xas/)(.*)" />
<action type="Rewrite" url="http://localhost:8012/{R:1}{R:2}" />
</rule>
<rule name="ws" stopProcessing="true">
<match url="^(ws/)(.*)" />
<action type="Rewrite" url="http://localhost:8012/{R:1}{R:2}" />
</rule>
<rule name="ws-doc" enabled="true" stopProcessing="true">
<match url="^(ws-doc/)(.*)" />
<action type="Rewrite" url="http://localhost:8012/{R:1}{R:2}" />
</rule>
<rule name="link" stopProcessing="true">
<match url="^(link/)(.*)" />
<action type="Rewrite" url="http://localhost:8012/{R:1}{R:2}" />
</rule>
<rule name="file" stopProcessing="true">
<match url="^(file)(.*)" />
<action type="Rewrite" url="http://localhost:8012/{R:1}{R:2}" />
</rule>
<rule name="debugger" stopProcessing="true">
<match url="^(debugger)(.*)" />
<action type="Rewrite" url="http://localhost:8012/{R:1}{R:2}" />
</rule>
</rules>
</rewrite>
<staticContent>
<mimeMap fileExtension=".mxf" mimeType="text/xml" />
<mimeMap fileExtension=".json" mimeType="application/json; charset=UTF-8" />
<clientCache cacheControlMode="DisableCache" />
</staticContent>
</system.webServer>
</configuration>
Ok. After some further testing, the issue can be resolve by adding an extra MIME type for JSON files, as suggested by Jaap.
<mimeMap fileExtension=".json" mimeType="application/json" />
The browser that I used for testing clearly had some cashing issues, and because of that I thought it did not work. However, after fully clearing the cache (I used CTRL+F5 multiple times, but that is not enough appearantly), it started to work.
I did a new release of the MX7 version of our application, and added the JSON MIME type BEFORE the update. That way, the application worked directly after starting up.
Thanks for all the help!