HTTP Error 502.5 – Process Failure
Don’t worry. Nothing on our server or your site is broken. You just need to modify the web.config file a bit or create one in the appropriate directory because the AspNetCoreModule is the default handler for processing files.
I’ll show you how in this guide where I have an ASP.NET Core 1.0 application in the root and WordPress in a sub-directory. Since I don’t want to memorize web.config markup language, I’ll let IIS Manager do most of the work for me.
Log into your site using IIS Manager and highlight the folder WordPress was installed to, so that the web.config file in that directory will get modified or created if there isn’t one.
Double click on the Handler Mappings module.
On your right, select View ordered List…
Using the Move Up/Move Down Actions, move PHP##_via_FastCGI to the top where ## represents the PHP version number that you are using. This will create the necessary markup in the web.config file in the WordPress directory without affecting your other web.config files.
Now click on View Unordered List…
Highlight aspNetCore and click on Remove. Don’t worry, this doesn’t delete the AspNetCoreModule. It just removes the handler mapping (i.e. entry in the web.config file), and voila, your PHP application should be working again.