HTTP Error 500.30 - ANCM In-Process Start Failure

I host an aspnetcore website on a Windows Server 2012 R2 running IIS on Amazon AWS and it’s generally fast and stable.

However, the past two nights the server has restarted unexpectedly leaving the website down with the following error message:

HTTP Error 500.30 - ANCM In-Process Start Failure

The first night a simple IISRESET command was all that was needed to get the site running again, however, last night it did the same thing.

Looking at Event Viewer I noticed the following:

Application '/LM/W3SVC/2/ROOT' with physical root 'C:\Path\To\Website' failed to load clr and managed application. Managed server didn't initialize after 120000 ms.

So, doing some googling I came across an article suggesting that An x86 app is deployed but the app pool isn’t enabled for 32-bit app.

This suggests that:

For an x86 framework-dependent deployment (<PlatformTarget>x86</PlatformTarget>), enable the IIS app pool for 32-bit apps. In IIS Manager, open the app pool's Advanced Settings and set Enable 32-Bit Applications to True.

Following those instructions the setting in IIS I changed then looked like this:

An IISRESET for good measure and the site is back up again.

I still need to see why Windows is restarting at approximately the same time each night the past few nights but if it does I hope to have solved the HTTP Error 500.30 - ANCM In-Process Start Failure error.

Success? 🎉